BigJimny Wiki - User contributions [en-gb]

Talk:Tyre selection and usage - best practices

2017-03-19T02:53:09Z

NelsonB:

Dear Bosanek,

you have made a very good job about tyre options for the jimny. I would like to make some contributions, but would like to know if the intention is to maintain a UK focus, or to enlarge the scope to a more global approach. Recently, jimny has been made in Brazil, in many different versions, including 215 tyre size, diferent bumpers and so on. So would like to know if a global approach is desired. Also, there are many different tyre size availability in some brands, from country to country. For instance, Michelin south america developed the ltx force (it´s been replacing the LT /AT2). This tyre had the 205 75 r15 size, and was made considering the terrible south american contryside roads. http://www.michelin.com/fre/presse/Presse-et-actualites/actualite-michelin/Innovation/MICHELIN-LTX-FORCE-la-meilleure-solution-quelle-que-soit-votre-route.

Regards
Nelson

Hello Nelson,

First of all - thank you for the commendation. I did my best to cover the topic to its fullest, most by the original research.

Since I am not from UK (I am from Bosnia and Herzegovina, also in Europe), my personal goal is to enlarge the scope of any Jimny wiki article to the global level.

However, my personal opinion is that each writer should take care to clearly indicate any country-specific and region-specific information which they add to any wiki article.

For example, the information about tyre pressures is a global one, not region specific. But in another example, information about Brasilian Jimny tyre sizes should clearly be mentioned in its own subchapter, in order to prevent confusion to readers who are not from South America.

Regarding tyre models and sizes,
I keep my personal table of worldwide available tyre models and sizes which I linked as read only to this wiki article. I welcome anyone to inform me about new tyre models or region-specific tyre models which I omitted from my table. My table is naturally european-based as I am most familiar with that tyre market. I will any new contributed information to my table as soon as possible. I have already added this Michelin model to my table. If you have information about any other tyre models, please let me know.

[[User:Bosanek|Bosanek]] ([[User talk:Bosanek|talk]]) 14:31, 16 January 2017 (UTC)

Hi Bosanek, I am confident that this approach will work great and so I will slowly dosome modest contributions. I would like to say that I did not work for, or have any benefits from Michelin, just almost had accident 2 times with pirelli tyre bubles exploding in highway.

For your table: Michelin Latitude Force is made in 205 70 r15 size in Brazil (http://www.michelin.com.br/tudo-sobre-carros/pneu/SUV-e-4x4/Misto/LTX-Force.html). Michelin also have the Latitude cross, a unidirectional AT tire, more prone to less off road use. It is available in 215 75 r 15.(http://www.michelin.com.br/tudo-sobre-carros/pneu/SUV-e-4x4/Misto/Latitude-Cross.html?xref=&yref=).

Brazilian 215 75 15 experience: About tyre pressure: Brazilian suzuki indicate 28 psiwithout weight (4 tyres) and 29 front 30 rear with full weight, for the 215 75 15 tyre size. This pressure raised a great debate between brazilian owners. I had experienced many part failures (king pin, wheel bearings/shocks short lived), but was fontunately enough to receive 3 reapirs and many parts even after 3 years warranty, by the brazilan suzuki.Today, majority of jimny with 215 tyres uses lower tyre pressures (23 front 26 rear (empty) and 23 f 29 rear (full) or lower. In loose beaches sand, I was able to use 9psi without problems.

Also, brazilian jimny "for sport" model, have a unique bumper, that resolved tyre-bumper problems. However, the 2017 model, changed back to 205 size, and we still dont know if it is based in economical crisis, or something technical between brazilian and japanese suzuki.

I am very interested in 195 85 r 15 sizes. Kuhmo road venture tires had the size in catalogue, but unfortunately Kuhmo did not sell then in Brazil, nor Argentina. (http://www.kumhoargentina.com/blank)

regards!

Hello, Bosanek,

made some minor changes (most cases). I will find interesting to have a chapter about the use of snow/mud chains after the MT tyres, as tyres and chains are a way to arrive to some ends (in this case, traction). In some countries of South America, and some regins of some countries, you could not drive if you don´t have a snow/mud chain. Because o f that, many people prefer to have AT tyres plus the chains them having MT tyres plus chains. In some jungle roads, you could not pass without chains, but a MUD tyre could not endure the "good" paved road untill asphalt end. To made things worst, in many country/places the use of chains/agressive remould tyres could be an enviroment crime. I enter the BFG AT KO on the prefered tyres, because it is almost everybody preference down here (where grabbers are only available as 225 75 15 and Goodyears Wranglers as 205 70 15). Final suggestion in the end of the text explained. Regards!

Hello Nelson!

I apologize for this large delay in response. I forgot to reply!

I added those two Michelin tyre models into my tyre model table.

That information about factory tyre pressures on 215 / 75 / R15 tyres on Brazilian Jimnys is very interesting! Factory tyre pressures on 205 / 70 / R15 tyres is 23 PSI front and 26 PSI rear. It makes NO sense to use HIGHER pressures on larger tyres. In fact, LOWER pressures than 23 PSI front / 26 PSI rear should be used!

There is a simple technical explanation of the principle (read my new chapter about tyre pressuers in this article).

I am still investigating on a relatively simple formula to calculate how much to reduce the on-road tyre pressures with larger tyres.

I would '''roughly''' use the on-road pressures on those 215 / 75 / R15 tyres circa 20 PSI front and circa 23 PSI rear (I have not done a precise calculation now).

So, 2017 "4work" and "4sport" Brazilian Jimnys use standard 205 / 70 / R15 tyre size?

Regarding tyre size 195 / 85 / R15, I have never seen a tyre in that size listed. I have however seen several tyre models in 195 / '''82''' / R15 size (look at my tyre models table).

Regarding your additions about snow/mud chains, that information is welcome. I did not know about that. It is definitely a good idea to use AT class tyres + mud/snow chains, instead of just MT tyres.
You just have to be careful about clearance between the tyre and the surrounding bodywork. If a larger AT tyre is used, there might not be enough space around the tyre to fit the chains, or the chains might destroy the bodywork. I wrote that in this article.

Kind regards!
- Bosanek

Hi Bosanek!

Your stuff about dif size uses is great! About repair too!

Yes, the pressure recomendation for the factory 215 75 was probably an error. Yes, 2017 Jimnys forSpor and For Work models came back to 205 size!
I just received a pair of Pewag off road chains, but the patagonia season is gone now. I will give then a try during the winter in some frozen roads in southern mountains here. The 195 85 I saw in Brazilian and Argerntina Kumho site. The size was not sold in this countries but was at a chart. Both sites now changed....
Best regards,

Nelson

Tyre selection and usage - best practices

2017-03-19T02:06:32Z

NelsonB: only correct the lift size of 215 lifted JImny´s from Brazil and those models by year

{{intro-notes}}

== Introduction ==

* One of the most common questions about improving vehicle's all-terrain performance and endurance is "what is the most effective modification to apply to my vehicle?".
* Well, using proper tyres, and using them properly, is arguably the most effective vehicle "mod" for all-terrain use!

{{note|"Most effective" can generally mean in the context of cost, performance, simplicity or endurance. Using '''proper''' tyres '''properly''' can be the most effective "mod" in all of those ways!}}

=== Overview of the topics covered by this document ===

# Choosing a proper tyre type for the desired usage;
# Choosing a tyre size (with various factors);
# List of various tyre models with remarks;
# Best practices on tyre usage (wheel rotation, wheel balancing, air pressures, rim and tyre repairs);
# Use of tyre chains for snow and mud conditions;
# Special situations and combinations;

== General remarks ==

=== Introduction ===

First of all, some basic remarks about using tyres on four wheel drive vehicles. Each remark is explained in detail in various chapters of this article.

=== Constraints on tyre combinations ===

* Inherent restriction of most four wheel drive transmission systems (Jimny's included) is that the vehicle has to use all four tyres of the same profile (size).
* Furthermore, all four tyres should be the same model and have a very similar tread depth (even small differences between rotational friction and wheel circumference among wheels can damage the transmission in the long term).
* This limits the combinations when choosing (buying) tyres.

=== The spare (5th) tyre ===

* The stated restrictions also apply to the spare (5th) tyre, which must not be overlooked!
* The spare wheel and tyre should be actively used in a 5-tyre rotation scheme.
* Topic of spare tyre utilization has its own dedicated sub-chapter: [[#Spare wheel and tyre usage|Spare wheel and tyre usage]].
* People who venture into serious expeditions and overland travels usually use '''six''' identical wheels and tyres in a six-tyre rotation scheme.

=== Tyre (air) pressures ===

* Frequent checking (and adjusting) of tyre air pressures is much more important for all-terrain use than for ordinary on-road use.
* Reason: tyre pressures significantly affect all-terrain traction as well as the risk of tyre damage (tyres get hotter with low pressures, for example).
* The topic of tyre air pressures has its own dedicated sub-chapter: [[#Tyre air pressures|Tyre air pressures]].

=== Wheel (dis)balancing ===

* Wheel (dis)balancing is a much more prominent issue for all-terrain use, especially for Jimnys as they are notorious for developing a [[Death Wobble|"death wobble"]] issue.
* It is a genetic trait derived from their short wheelbase and solid (rigid) front axle suspension design.
* See the sub-chapter [[#Wheel balancing|"Wheel balancing"]] for more details.

=== Tyre profiles ===

* For all-terrain use, '''higher profile''' tyres are always preferred against '''lower profile tyres'''.
* Reasons: higher profile tyres cushion the ride better on all-terrain both for the vehicle and for the passengers, they decrease the chance of rim damage, and they allow better air pressure management.
* The only disadvantage of "tall" tyres is worse performance when the vehicle corners fast in a bend, but it is insensible anyway to do so in a high, narrow, wobbly, jumpy, twitchy vehicle.
* Therefore, putting oversized rims with thin tyres on a 4WD vehicle is like putting ballet shoes on a village farmer.

* A "higher profile" means a "taller" tyre (taller tyre sidewall).
* The '''second''' number in tyre's sizing specification determines its "tallness" as a percentage of its width.
* An example: for a 205 / '''70''' / R15 tyre, the second number says that its sidewall height is 205 mm * 0,7 = 143,5 mm.
* Sometimes a narrower tyre with a higher second number is actually taller than a wider tyre with a lower second number!
* An example: 195 / 80 / R15 is taller than 205 / 70 / R15 (156 mm sidewall length vs 143,5 mm sidewall length).

== Choosing a proper tyre type for the desired usage ==

=== Introduction ===

Tyre designs for passenger and light truck vehicles can be (among other ways) designed and built for regular "on road" use (the vast majority of tyre models) or (to an certain extent) for all-terrain use.

The difference between those two design approaches is not just in the tread pattern (traction capability). Another equally important aspect is tyre's robustness (resistance to various types of trauma, which '''regularly''' occurs off the asphalt), which is generally given dedicated design attention for all-terrain tyres (based on tyre's exploitation expectancy). For ordinary road tyres, robustness is barely considered on itself. Also, tyre's adaptability to different weather conditions is also sometimes given more design thought when designing all-terrain tyres.

There is no official standard to differentiate various kinds of all-terrain tyre designs.

There are three "industry categories" of all terrain tyre designs, based on loose practical usage classifications (from "worse" to "best"):
* 1. HT - "Highway Terrain"
* 2. AT - "All Terrain"
* 3. MT - "Mud Terrain"

Tyre manufacturers usually use this classification to position their all-terrain tyre models in their marketing catalogue.

* HT tyres generally have the best on-road performance and worst off-road performance of all three categories.
* MT tyres generally have the opposite performance characteristics.
* AT tyres are generally in the middle - being good but not great for both.

* Since these are loose classifications, there are "weaker" and "stronger" tyre models in each category, so each tyre model should be precisely evaluated on its own.
* For example, Dunlop Grandtrek AT20 could be classified either as a "mild AT tyre", or as an "extreme HT tyre" :).
* Another example is Uniroyal Laredo HD/T, which could be classified either as a "mild MT tyre" or as an "extreme AT tyre".

A special case are retreaded (remoulded, "protect") tyres. Read more about them in the subchapter below.

=== HT tyre class ===

Main traits:
* Highway terrain tyres are generally meant to be used predominantly on road, with only slight & light off road excursions (possibly rougher gravel, some grasslands, etc.).
* The overall tread design and depth of HT tyres is generally quite similar to ordinary road tyres.
* That means that HT tyres generally have equally proficient on-road performance and endurance even for sharp or very fast driving (and similar fuel economy), but almost equally bad all-terrain performance as ordinary road tyres.
* However, having the "terrain" part in their name, HT tyres should be slightly more robust than ordinary road tyres.

Conclusions:
* For (almost) always on-road driven all terrain vehicles, HT tyres can be an optimal choice if the vehicles are driven sharply or at high speeds.
* HT-class tyres are always recommended over ordinary on-road tyres for two reasons - they should be more robust and they at least formally "suit" the all-terrain image of the host vehicle.
* However, AT tyres are definitely a better choice if proper all terrain driving is even occasionally performed, and/or if the vehicle is not driven fast or sharply.

=== AT tyre class ===

Main traits:
* All terrain tyres are generally meant to be used in mixed on-road and all terrain conditions (anywhere between 30% and 70% of time for either).
* AT tyres usually have significantly rougher (and a bit deeper) tread design compared to HT and ordinary road tyres.
* AT tyres are a performance compromise which is usually hard to achieve.
* AT tyres are generally good on-road except for sharp or very fast driving, and generally good off-road except for boggy and/or harsh conditions (deep mud, deep snow, sharp rocks, river crossings ...).
* AT tyres are usually significantly more robust than ordinary road tyres.
* AT tyres should slightly impact fuel economy.
* AT tyres can be a challenge to balance properly.
* Many AT tyres are "all season", which further adds to their "all terrain" value (for example, mountaineers can encounter ice and snow even in June and as early as September).

Conclusions:
* For all-terrain vehicles which are used for everything - commuting, intercity travel, and various all terrain conditions, AT tyres are the solution.
* AT-class tyres should not present a jeopardy on the road, and they should be a trusted companion off the road, in the sense of traction and in the sense of reliability.

=== MT tyre class ===

Main traits:
* Mud terrain tyres (also called "Maximum Traction") are generally meant to be used predominantly off road, with only slight easy-going on-road excursions.
* MT tyres usually have very deep and striking ("tractor looking") tread and sidewall appearance, and very high robustness capability through various reinforcements.
* MT tyres excel in boggy and/or harsh conditions (deep mud, deep snow, sharp rocks, tree roots, river crossings, etc.) and offer the best protection against punctures, cuts and chipping.
* However, MT tyres are generally noisy on the road, wear faster and present a real jeopardy if not driven slowly and carefully on a wet road and especially on packed snow or ice.
* Also, MT tyres usually significantly affect fuel economy.
* Due to their coarse construction, MT tyres can be very hard or impossible to balance properly.

Conclusions:
* For all-terrain vehicles which rarely touch the asphalt and are used on tough terrain, MT tyres should be the weapon of choice.
* However, MT-class tyres can be a jeopardy on regular road surfaces and they wear out faster and louder on road.
* Also, if not balanced entirely, MT-class tyres will cause issues on road.

=== Retreaded (remoulded, "protect") tyres ===

Main traits:
* A retreaded tyre is a recycled tyre - it is a previously used and worn out tyre, which had its worn tread surface grinded off, and a new tread (which can have completely different pattern from the old one) glued on.
* The material of the new tread is specific to the retreading "factory".
* Therefore, retreaded tyres are essentially "tyre zombies" - they are old, worn tyre carcasses which have been restitched and brought back to life like Frankenstein.

Notes on tread patterns:
* Retreaded tyres are produced in all kinds of editions and flavors, with their treads typically mimicking a well known brand name tread pattern.
* They can mimic any tread pattern, either of slick and smooth road tyres, summer or winter tread designs, as well as heavy-duty AT, MT or even more extreme agricultural and industrial tread patterns.
* They can also be made with a custom tread design of any appearance that you can imagine.

Advantages of retreaded tyres:
* They are quite cheap (usually cheaper than any brand name tyre).
* They are ecological (recycled material).
* There is a wide and colorful choice of tread patterns, especially the extreme traction ones.

But there is a cost to pay. Read on.

Disadvantages of retreaded tyres:
* Bear in mind - if a tread appears the same like from a brand name tyre model, it does not mean that the materials and compositions of the tread are the same (affecting grip, wear rate, etc.).
* Also, you hardly ever know which actual tyres were used for resurrection - for all-terrain duty, the strength and robustness of tyre's sidewalls are equally important as the tread pattern.
* There are also horror stories of retreaded tyres failing catastrophically during high speed driving - the tread layer actually glues off from the tyre carcass. The consequences don't look pretty from any angle of view.
* In some countries, an aggressive tread remoulded tyre could render an environmental fine in some back-country roads.

{{warning| Beware that Jimnys (as most vehicles with solid front axles) are highly susceptible to developing a [[Death Wobble|"death wobble"]] issue produced by disbalance or play in their front suspension. Improper wheel balance is highly likely to trigger it. Retreaded tyres (even those with ordinary on-road treads) are notorious for being hard or impossible to balance.}}

[https://docs.google.com/spreadsheets/d/1-1RXKtrBykdw7V9X1WX3jLXpSdygKb8ji3y1WJZhR0g/pubhtml '''Here'''] is a document (''made by forum user [https://www.bigjimny.com/index.php/forum/profile?view=user&userid=16580 Bosanek]'') which summarises all arguments FOR and AGAINST using retreaded tyres.

== Choosing tyre size ==

=== Reasons and benefits ===

Why would you want to change your tyre size?
* Well, for all terrain vehicles, the usual strive is to increase ground clearance.
* Increasing wheel diameter by increasing tyre profile (the second number in tyre size marking) is the most effective way to achieve this.
* It lifts the entire vehicle (including the axles!), and is dead simple to do for mild increases.
* There are additional advantages of increasing the tyre profile ("tyre height") - as mentioned in the [[#Tyre profiles|"Tyre profiles"]] chapter.

{{note|When a wheel diameter is changed by a certain amount, the vehicle's (and the axles') ground clearance will change by only half as much (by the amount of wheel's radius change). Basic school geometry explains why.}}

=== Issues and risks ===

'''However, increasing the wheel circumference/radius incurs the following technical issues:'''
# The vehicle will accelerate harder / slower and will move faster downhill on engine braking (in any gear);
# Transmission will have a heavier duty to perform, leading to premature wear in the long term;
# Fuel economy is slightly decreased (mostly because of harder acceleration);
# Speedometer and tachometer measurement will change as much as the circumference has changed;
# Larger tyres might not fit - they might rub on the bodywork when the front wheels are turning left/right or when the suspension is compressed on uneven terrain;
# The larger spare tyre might not fit in its spare position (contact with some vehicle body parts) and/or in its case/cover;
# Using snow/mud chains can be risky or impossible, because of (much) less available clearance between the wheels and the surrounding bodywork and mechanical components. However, 4WD vehicles might need snow/mud chains only on steep icy terrain, or for plowing very deep snow. A 4WD vehicle with AT tyres also could benefit of chains in deep soft muddy terrain.

The extent / severity of these issues highly depends on how much the wheel radius has been increased. They should be negligible to slight at most, if you stay roughly within +-3% of the factory size.

Using too wide tyres also induces some of these issues and risks.

'''Some of these technical issues can be (and usually have to be) remedied in case of significant tyre size increases:'''
# Impact on vehicle's acceleration and engine braking can be remedied by altering the transmission gears ("regearing").
# Regearing the transmission will also remedy the load on some parts of the transmission, but some parts, like the wheel bearings for example, will remain under heavier duty;
# Tyres can be made to fit properly by two methods - firstly by lifting the vehicle's body or suspension and/or secondly (usually irreversibly) altering the bodywork (trimming the wheel arches, inner arch linings, etc.), the extent of which highly depends on tyre size;
# In Jimny's case, the larger spare tyre can be made to fit to the tailgate by installing a spacer on the tyre holder, but the spare tyre vinyl cover or hard spare tyre case has to be custom-made (if badly needed);
# Very wide tyres significantly increase the drag force when pulling a bogged vehicle from deep mud.

Some of the mentioned remedies can be quite expensive to apply, and might also imply further modifications.
For example, higher suspension lifts require modified radius arm bushes, brake hoses, propeller shafts, adding wheel spacers, buying a new loan at the bank ....

{{warning|Using a non-factory tyre size might be illegal or require some vehicle recertification, depending on country or region.}}

=== Impact of larger tyres on fuel economy ===

==== Introduction ====

* Using larger tyres certainly negatively impacts fuel economy.
* However, calculating how much is not straightforward!
* There is an important factor of calculation which most people do not take into account, and then they get skewed results.
* The factor is that, with larger tyres, the odometer will record less distance than the vehicle has actually traveled.
* '''Without''' counting this factor in, the fuel consumption figures get skewed for the worse (the calculated consumption falsely shows to be even higher than it actually is).
* To count this factor in, you have to calculate the percentage of odometer reading mismatch, and multiply it with the odometer reading (to correct the reading to the true value).
* Read more below for the details.

==== Full details ====

The standard method of calculating fuel consumption in practice (in "l / 100 km" measuring unit) is:
* Fill in a full fuel tank of fuel, and note the current odometer reading.
* Drive until the fuel tank gets to a (preferably) reserve level.
* Fill in a full fuel tank of fuel again, and note the current odometer reading and how much fuel was poured in.
* The amount of poured fuel during the last fill is the parameter "F".
* Calculate the difference between the two odometer readings, that is the parameter "S".
* The formula to calculate the fuel consumption "C" is: '''C = 100 * F / S'''.

An example:
* After traveling for 385 km, the amount of poured fuel to fill a fuel tank was 34,5 l.
* The calculated fuel consumption: C = 100 * 34,5 / 385 = '''8,96''' l / 100 km.

* This method of calculation works just fine when using stock sized tyres.
* When using larger tyres, the odometer (and speedometer) reading (parameter "S") is skewed (incorrect) because the device is calibrated for the stock tyre size (wheel ''circumference'').
* The circumference of a wheel in fact represents the path that the wheel travels for one full wheel rotation.
* The speedometer and odometer only count the wheel rotations (by counting the rotations of some particular gear in the transmission), and they expect the wheel circumference to be close to the theoretical stock size (it always varies slightly due to tyre construction and varying tread depth).
* Therefore, when a larger diameter wheel is used, the odometer will count less distance than the vehicle has actually traveled in real life.
* The amount of skew is directly proportional to the amount of wheel circumference change.

An example:
* The theoretical diameter "D1" of a stock sized tyre (205 / 70 / R15) is 668,0 mm.
* Its circumference "C1" is: C1 = D1 * pi = 668,0 * pi = 2098,58 mm.
* The theoretical diameter "D2" of a 215 / 75 / R15 tyre is 703,5 mm.
* Its circumference "C2" is: C2 = D2 * pi = 703,5 * pi = 2210,11 mm.
* The difference: C2 - C1 = 111,53 mm = 11,2 cm.
* That is how much additional distance the larger wheel will travel with each wheel rotation!
* It might not look like much for one wheel rotation, but it's actually a (C2 / C1 - 1) * 100 = 5,31% increase in wheel circumference.
* This directly translates to '''5,31%''' increase in the path traveled, for '''any''' distance.
* That means, when your odometer shows that you have traveled 1000 km with these larger tyres, you have actually traveled circa 1053 km!

* Now, if you keep on using the standard fuel consumption calculation formula with the larger tyres (without factoring in the skew in the odometer reading), you will get skewed results.
* Because you have actually traveled more distance (and therefore used more fuel) than your odometer shows, the calculated fuel consumption will be higher than it actually is.
* You will find many driver reports/complaints on the Internet of increased fuel consumption after installing larger tyres, where many drivers even provide "calculated" fuel consumption figures.
* However, most of those people have not factored in this odometer reading skew, rendering their results incompetent.
* If someone has not mentioned that they had factored in the skew in the odometer reading when calculating fuel consumption with larger tyres, than don't trust their fuel consumption figures.

To continue on the above to examples:
* You have 215 / 75 / R15 tyres.
* Their theoretical circumference is 5,31% larger than the theoretical circumference of stock-sized tyres (205 / 70 / R15).
* The recorded odometer difference "S" between two full fuel tank fills is 385 km.
* The amount of filled fuel "F" during the last fuel fill was 34,5 l.
* Standard calculation (''without'' factoring the skew in odometer reading): C = 100 * F / S = 100 * 34,5 / 385 = '''8,96''' l / 100 km.
* However, if you factor in the skew in the odometer reading: S' = S * 1,0531
* Now, the new ('''correct''') calculation: C = 100 * F / S' = 100 * 34,5 / (385 * 1,0531) = '''8,51''' l / 100 km!
* This is a difference of '''0,45''' l / 100 km!

==== Conclusion ====

* While the fuel consumption does slightly increase with larger tyres, it isn't nearly as much as standard "calculations / measurements" would indicate.
* To accurately calculate / measure the fuel consumption with larger than stock size tyres, you need to determine the percentage of change in wheel circumference compared to stock size, and then include that factor in the standard formula for calculating fuel consumption.
* The percentage of change in wheel circumference is parameter "P".
* The final formula (l / 100 km unit) is: '''C = 100 * F / (S * (1 + P/100))'''

You can get the wheel circumference numbers and percentages for typically used tyre sizes on Jimnys in [https://docs.google.com/spreadsheets/d/1qwxmEIQ98WjkWoMsE49TNWHG4xq8P6C0cQZJcriiiL8/pubhtml?gid=0&single=true '''this table'''] about Jimny-compatible tyre sizes, which was made by forum user [https://www.bigjimny.com/index.php/forum/profile?view=user&userid=16580 Bosanek].

== Jimny factory tyre size and approved sizes ==

* The factory tyre size on all Jimnys is '''205 / 70 / R15'''.
* Exceptions are some JDMs (Japanese domestic models) (possibly 175 / 80 / R15 ?) and some Brazilian models (215 / 75 / R15).

* According to some South African and Australian forums (example: [http://www.4x4community.co.za/forum/showthread.php/67086-Approved-Jimny-tires this forum topic]), their local Suzuki dealers' official policy is to allow +-3% variation in wheel diameter.
* Therefore, if your Jimny is under warranty (or you want to be mechanically moral), +-3% is your expansion border.

{{note|If you want to be certain about this matter, then check with your local Suzuki dealer!}}

== Compatible & interesting tyre sizes for Jimny rims ==

=== Quick and simple decision ===

The three most popular, non-extreme size upgrades are to:
# '''205 / 75 / R15''' - (ground clearance and tyre's sidewall height increase by cca. '''10 mm''')
# '''195 / 80 / R15''' - (ground clearance and tyre's sidewall height increase by cca. '''13 mm''')
# '''215 / 75 / R15''' - (ground clearance and tyre's sidewall height increase by cca. '''18 mm''')

* However, even these non-extreme sizes '''may''' impose certain risks of collisions between tyres and the vehicle body in some vehicle configurations.
* That mostly depends if the vehicle has 2nd gen. front bumper or not, if it has front mudflaps or not, if wheel spacers are used, etc.
* The risk is generally the lowest with the first size in the list, and the highest with the third size in the list.

* Any tyre size upgrade will also introduce certain deviations in vehicle's driving characteristics (road handling, acceleration, top speed, engine braking, transmission's stress).
* However, for these three non-extreme size upgrades, those deviations range from "negligible" to "small".
* The first size in the list is the least deviant, as it provides the smallest diameter change, while also keeping the same tyre width.

* Bear in mind that while the first size '''might''' be allowed by Suzuki (depending on company's regional policy), the second and third sizes are definitely not allowed by Suzuki (regional exceptions apply).
* Also bear in mind that ANY tyre sizes apart from those which are strictly specified in vehicle's handbook are prohibited in certain countries!

{{warning|MT class tyres, and especially "remoulded" (retreaded) tyres, typically deviate significantly from their theoretical sizes (they tend to be quite larger)!}}

==== Regarding "tyre vs. vehicle body" collision risks ====

Sizes 205 / 75 / R15 and 195 / 80 / R15 generally have no risks of collisions with the vehicle's body, with two exceptions:
* If you have a 2nd gen. front bumper (see below), you might have to straighten it if it is sagged, or trim it just slightly (invisibly) on the bottom (simple job with a grinding tool).
* If you have front mud flaps, you might have to trim a plastic spacer behind them by approx 10-15 mm (which is easy to dismount and mount).

Size 215 / 75 / R15 could be more problematic:
* It may require some trimming of the bottom of the front bumper, especially if it is a 2nd gen. bumper.
* Front mudflaps will probably need to be removed.
* The spare tyre might contact with the rear bumper.
* Wheel arch trimming is generally not needed, except if wheel spacers are used without a lift.
* Brazilian "HR" (2010-2012) "4sport" and "4work" (untill 2016) Jimny editions (which came with "215 / 75 / R15" tyres from the factory), also came with an approximate 25 mm body lift from the factory (to remedy the collision risks).
* The Brazilian "4sport" edition also had a minimalist front bumper, which increased the clearance in front of front tyres (collision risk when steering) and provided higher approach angle.

This was a quick and simple guide to the issue of tyre sizes.

{{note|If you have or expect collision issues between your existing or planned tyres and the vehicle, you can remedy them by [[Lifting the vehicle|'''Lifting the vehicle''']] and/or by [[Wheel arch trimming|'''Trimming the wheel arches''']] and/or by trimming the front bumper.}}

{{note|If you use a pendant-style towbar-mounted bicycle carrier, a wider spare tyre might collide with the bicycle carrier. This depends on how long the tow ball + tow neck section is. Read [[Towbar|"'''Towbar'''"]] and [[Bicycle carriers|"'''Bicycle carriers'''"]] wiki articles for more information.}}

=== Thorough consideration ===

* On the other hand, if you want to dig neck deep into the issue of tyre sizes, study [https://docs.google.com/spreadsheets/d/1qwxmEIQ98WjkWoMsE49TNWHG4xq8P6C0cQZJcriiiL8/pubhtml?gid=0&single=true '''this table'''] on Jimny-compatible tyre sizes, which was made by forum user [https://www.bigjimny.com/index.php/forum/profile?view=user&userid=16580 Bosanek].
* That table shows all compatible & interesting tyre sizes which fit on Jimny's stock steel and alloy rims.
* The table also contains many compiled remarks of risks and issues for each non-stock tyre size.
* Those issues are rarely taken into consideration until it is too late!

{{note|The availability of different tyre models in desired tyre size will vary significantly. Not all tyres are manufactured in every listed tyre size for every market or all the time.}}

* As it is evident from the table, even if you choose to stay within Suzuki's alleged 3% allowed wheel diameter increase, there are several tyre profiles which can be used to achieve the goal of higher ground clearance.
* It is preferred to achieve the goal by increasing sidewall height (second number in tyre profile sizing code) instead of altering tyre width (first number in tyre profile sizing code).
* Maximum "gain" is achieved if both are increased at the same time.

== Tyre models in Jimny-compatible sizes ==

* There is a wide variety of HT, AT and MT class tyre models which are available in Jimny-compatible sizes.
* It would be a pity to use an ordinary limousine road tyre instead!

* [https://docs.google.com/spreadsheets/d/1jFMegEyyC1dJex8oPji3h8ASGHHONHgX44albDzM0qg/pubhtml?gid=1691702446&single=true '''This table'''] (''made by forum user [https://www.bigjimny.com/index.php/forum/profile?view=user&userid=16580 Bosanek]'') contains the list of all brand-name HT, AT and MT tyres which he has found on the worldwide market.
* In addition to the list of tyre models, that table also contains the availability of each tyre model in most popular Jimny-compatible sizes!
* A lot of time has been spent populating that table, and adding custom remarks there.
* The table is still incomplete in some details, but will be updated from time to time.
* The sizing availability is the most incomplete, as it takes a lot of investigation to fill the required data for each tyre model.

{{note|Not all of those tyre models in the list are available in sizes which are compatible for Jimny. Sizing availability might depend on the market, and can change for better or worse at any time.}}

* Therefore, once you settle on your desired tyre size, now you can browse through tyre models and choose the one which is available in that size and suits your criteria the best.

=== User experiences with certain tyre models ===

Here are the AT tyre models with which Jimny owners have had great or good experiences with:
* Goodyear Wrangler AT/SA+
* General Grabber AT (not AT2!)
* Continental ContiCrossContact AT
* BF Goodrich AT/KO

All three of those models have proven themselves as being very good on-road in any time of year, while also proving to be rather versatile off road.

Also, General has recently (09/2016) released model '''AT3''', which looks very interesting indeed. Avoid the model AT2, it is very old and deprecated one! Grabber AT2 is actually older than Grabber AT.

If you insist on heavy-duty off-road performance but still want to retain '''some''' on-road credibility, there are three MT class tyre models with which Jimny owners have been relatively satisfied with:
* Bfgoodrich Mud-Terrain T/A KM2
* Hankook Dynapro MT (RT03)
* Kumho Road Venture KL71
* [http://www.maxxis.co.uk/catalog/tyre-3-21-trepador-radial-m8060#sizes Maxxis Trepador M8060] ''(Martin Lines comment: I have found these particularly good on a standard Jimny)''

There are other good AT and MT tyre brands and models of course.

== Spare wheel and tyre usage ==

=== Introduction ===

* All proper all terrain vehicles, like Jimny, come with a full size matching spare wheel, which is the same as the other four wheels.
* That is for a reason.
* That spare wheel and tyre are not meant to be just carried around and sit idle all the time.
* For all terrain vehicles, spare wheel is not a fashion accessory nor a "dead cargo" - it is an important operational element of the vehicle, as well as an important safety device.
* Therefore, the spare wheel and tyre must not be overlooked. It should be actively used.

* Otherwise, there are multiple risks of staying stranded in the event of the simplest tyre puncture, or even damaging vehicle's transmission in the event that the spare wheel does indeed have to be used!
* If you use only four same tyres in a typical 4-tyre rotation scheme, you might easily end up with only three half-worn same tyres - useless for a 4WD vehicle.
* For example, a sidewall puncture is generally impossible to repair properly. You will have to discard the remaining three tyres and buy all four/five new tyres - what a waste.

However, there are some rules and restrictions when actively using five same tyres - read more in the following subchapters.

=== Using five identical tyres ===

{{note|Buy and use five same (identical) tyres! The spare tyre should not sit idle all the time! That is even written in Jimny's owner manual.}}

* The spare wheel and tyre should be actively and periodically rotated together with the other four wheels and tyres, and all should be the same.
* In other words, the 5th wheel and tyre should play an equal role and importance as the other four wheels and tyres.
* In case of an all-terrain vehicle like the Jimny, that gives you so much benefits, and only one downside - you pay 25% more at once when buying the tyre set.

[https://docs.google.com/spreadsheets/d/1svFOPe-Z1xS2BbiYvr3jQbAortqZevZy74VC9wdo9Dk/pubhtml '''Here'''] is a document (''made by forum user [https://www.bigjimny.com/index.php/forum/profile?view=user&userid=16580 Bosanek]'') which shows the rotation scheme, and also lists "FOR" and "AGAINST" reasons to actively use all five identical tyres in a 5-tyre rotation scheme.

* It is a good practice to rotate the tyres with every engine oil change.
* If you recently bought a set of four new identical tyres (they have not got worn more than 1-2 mm at most), you still have time to buy the fifth one (you don't need it yet, until the first rotation).

{{note|The five-tyre rotation scheme is especially suited to practice when using all-season tyres. Many AT-class tyres are all-season.}}

{{warning|If you have a hard or soft spare wheel cover, you won't be able to use it with a spare tyre which is larger than the stock size.}}

{{note|Five-tyre rotation scheme is '''not''' practical with tyres which have directional (uni-directional, asymmetric) treads, because each such tyre must be used on only one side of the vehicle for which it was made for. Unidirectional tyres typically have a "Rotation" with arrow mark on their sidewalls, indicating proper orientation. Therefore, when using five tyres, always use non-directional (bi-directional, symmetrical) tyres. Luckily, most HT, AT and MT tyre models have symmetrical treads, but there are exceptions. Beware of this!}}

=== Using a non-matching spare tyre ===

==== Introduction ====

{{note|Using (periodically rotating) a matching spare tyre together with the other four tyres is strongly recommended, as per the above subchapter '''[[#Using five identical tyres|"Using five identical tyres"]]'''.}}

However, if, for whatever reason, a non-matching spare tyre has to be used on a 4WD vehicle, special caution has to be applied in order to avoid expensive transmission damage!

This subchapter is a guide what to do in this unfortunate event.

First of all, a ''non-matching'' tyre in this context means any of the following:
* Different tyre size (width or height) than the other four tyres;
* Different tyre model than the other four tyres;
* Tyre's tread depth more than 1 mm or 2 mm different than the tread depth of the other four tyres;

The cause of the issue with using a non-matching spare tyre:
* Any 4WD transmission with a non-existing center differential (or when a center differential is locked) expects the same rotational speed and rotational friction from all four wheels.
* If that is not the case, the gears and shafts of the transmission literally tension and wind up because of the discrepancies caused by a non-matching wheel.
* If the tension and wind up become sufficiently high, something in the transmission '''will''' break.
* With a non-matching spare wheel in the game, the breaking point could be just a few wheel turns away!

==== Installation position ====

* With part-time 4WD vehicles like the Jimny, the non-matching spare wheel should always be used on the front axle.
* The reason is that the front wheels are disconnected from the entire transmission when the vehicle is in 2WD and 2WD-L mode, and therefore using a smaller wheel does not impact the transmission then.

So, if one of your '''front''' tyres get punctured, just replace that wheel with your non-matching spare wheel and tyre.

However, if one of your '''rear''' tyres gets punctured, the procedure would be:
# Remove the punctured rear wheel;
# Remove one good front wheel;
# Install that front wheel in the place of the punctured rear wheel;
# Install the spare non-matching wheel in the place of the removed front wheel.

That's a lot of work if it's hot, cold, wet, dusty, raining, windy or night time! But it is the only proper way.

* Now, when the non-matching spare tyre is on your front axle, as long as you don't engage 4WD, you should be fine.
* So, do your best to get to the nearest tyre repair workshop strictly in 2WD mode.
* If you have manually operating front wheel hubs, make sure that they are disengaged all the time.

==== Using 4WD mode with a non-matching spare tyre ====

If you get a puncture in the middle of offroading where you need 4WD to get to civilization, you are in trouble.

* After installing the spare non-matching wheel on the front axle per the above instructions, constrain the use of 4WD only when it is absolutely necessary.
* Disengage 4WD as soon as it is not strictly necessary, and engage it later when necessary again, and so on.
* If you have manually operating front wheel hubs, you have to engage and disengage them every time in sync with engaging and disengaging 4WD.

* Alternatively, using 2WD-L mode would be safe in regards of the issue of non-matching spare tyre, and it might provide enough aid to get you trough difficult sections instead of using 4WD.
* However, Jimnys have to be modified first in order to enable 2WD-L transmission mode.
* See the chapter [[2WD-L transmission mode]] for details.

* While 4WD is used, the size or friction discrepancy on one wheel will cause '''constant''' transmission wind up as long as the vehicle is moving in 4WD.
* However, as long as 4WD is used on rather slippery ground (snow, mud, very loose gravel), the wind up should be able to constantly relieve itself, without harmful consequences.
* In other words, one wheel will have to ''continously'' "underslip" in order to compensate for the discrepancy.
* Only very slippery ground can enable that.

* The most difficult situation would be with rather rocky or bumpy '''dry''' road, where you usually need to use 4WD-L 1st gear to pass slowly.
* Because the road is '''dry and/or rather solid''', there is not enough chance for the transmission to relieve itself of the continuous discrepancy (for a wheel to continuously underslip).
* Therefore, transmission damage in these conditions is quite likely!

* Therefore, if you have to use a non-matching spare tyre on a dry rocky or bumpy road, the best option is 2WD-L 1st gear.
* However, if your Jimny is not modified to have 2WD-L mode, it might be better to use 2WD 1st gear instead of 4WD-L 1st gear.
* That means you have to go through faster, or drive "improperly" by riding the clutch and/or the brakes.
* It is the driver's decision whether to risk the damage to the suspension done by going faster through rocks and bumps, or to the clutch if riding it, or on the other hand, to risk damage to the transmission in 4WD-L mode.

== Tyre air pressures ==

{{note|Changing your tyre pressures to suit the (off)road conditions is the '''most effective''' vehicle mod ever!}}

=== Introduction ===

* Learn and use the skills of tyre pressure management.
* The benefit is not just for improved traction, but also for improved ride comfort and reduced vehicle stress!
* In general terms, reducing tyre pressure by 20-30% from stock on-road pressure is the operating norm for hard (rough) gravel and general off-road conditions.
* For deep mud, deep snow, sand and other boggy conditions, even more pressure reduction can be used (but with caution).

{{warning|When tyre pressures are reduced (for any reason), vehicle's top speed should be limited to approx '''50 km/h''' / '''30 mph''' on tarmac roads, or ~ '''40 km/h''' / '''20 mph''' on gravel roads. Otherwise, the tyres might overheat and disintegrate prematurely!}}

=== Dependency of tyre pressures on axle load ===

* Required / recommended tyre pressure generally also changes with load (weight on the axle).
* The heavier the load, the more pressure (air quantity in the tyres) on that axle is required to carry it.
* For almost any vehicle, manufacturers specify different tyre pressures for different loads (for example - driver only, full passengers with cargo, towing a trailer, loaded cargo bay, etc.).
* For Jimny (as far as it is known), Suzuki has not specified different tyre pressures for empty and laden conditions.
* That is probably because the vehicle has such a small load rating (cca 300 kg at most - roughly 150 kg per axle!) that it does not matter that much.

=== Specific tyre pressures for Jimnys ===

* So, for a Jimny, the factory recommended on-road tyre pressure for stock size tyres ('''205 / 70 / R15''') is '''1,6 bar (23 PSI)''' front and '''1,8 bar (26 PSI)''' rear.
* Some Jimny owners even the tyre pressures to '''1,7 bar''' on all four tyres, for simplicity.
* When driving on gravel roads or general off road, it is completely fine (and even advisable) to reduce the tyre pressure by '''25-30%''' to '''1,25-1,15 bar (17 - 18 PSI)'''.
* The difference in ride quality is '''astonishing''', while the traction is significantly improved.

=== Effect of tyre size on tyre pressures ===

* When using tyres which are larger than stock size, all (both on-road and off-road) tyre pressures should be reduced from the above written numbers.
* Because it is the air itself (air molecules) that carries all the weight, the concept is to always have the same amount of air molecules in the tyre for certain road and load conditions.
* The larger the tyre, the '''more''' air molecules fit inside for the '''same''' tyre pressure.
* So, to achieve the presence of the '''same''' number of air molecules in the tyre regardless of tyre size, a '''lower''' tyre pressure has to be used with a '''larger''' tyre.

* There is no simple formula for calculating how much the on-road (and implicitly off-road) tyre pressure should be reduced with certain larger tyre sizes.
* This topic is still under investigation.

=== Measuring and inflating tyre pressure ===

* It is compulsory to carry a good quality tyre pressure measurement tool, and very desirable to have your own 12V air compressor.
* You can inflate your tyres at gas stations (their equipment is much quicker than your own compressor), but you ''generally'' should not trust the pressure measurement instruments at gas stations, as they could be '''wildly''' inaccurate!
* Trusting that a publicly (ab)used pressure measurement instrument at a gas station is accurate is like trusting that a prostitute has no STD.
* There are local exceptions of course, but this is a general rule.

* Deflating tyres can simply be done by the stone age era method - using sticks and stones.
* There are various cheap and expensive tools which enable faster and/or controlled tyre deflation.
* The quality and usefulness of those tools vary widely.
* Since tyres on Jimnys are relatively small (compared to most 4WD vehicles), the practice has shown that using the stone age method is generally sufficiently fast.
* In other words, the time savings provided by various tyre deflation tools are hardly worth the cost and effort on such relatively small tyres.
* Employing a passenger to deflate two tyres in parallel with you (using sticks and stones) is cheaper and faster than using the tools.
* After several inflation-deflation iterations, you will be able to roughly calculate how much time you need to deflate your tyres from the on-road tyre pressure to your typical off-road tyre pressure.
* For example, one experience says that it takes approximately '''25 seconds''' to reduce a '''205 / 75 / R15''' tyre's pressure from '''1,7 bar''' to '''1,20-1,15 bar'''.
* This way, you won't have to check the tyre pressure several times with the pressure measurement tools when deflating each tyre.

== Wheel balancing ==

Jimnys, as all vehicles with solid front axle suspensions, are susceptible of developing a "death wobble" vibration at a certain speed range.

{{note|Read more about death wobble in '''[[Death Wobble]]''' wiki article.}}

Since wheel disbalance can easily cause death wobble, you need to take additional considerations in order to balance your wheels properly.

You can educate yourself about wheel balancing issues at the dedicated chapter "Wheel balancing" of the above mentioned death wobble wiki page: '''[[Death Wobble#Wheel balancing|Wheel balancing]]'''

== Wheel damages and repairs ==

=== Introduction ===

* In the context of this chapter, the term "''wheel''" refers to the entire metallic wheel/rim on which a rubber road tyre is mounted.
* It is not unusual for a wheel to become damaged.
* Generally, the risk is higher when driving on unpaved roads or off road, for example on rough gravel roads or on rocky terrain.
* However, the damage can occur even on a promenade, for example when hitting a street curb or a pothole on the road.

==== Notes on wheel (mis)alignment ====

* Forces sustained by strong wheel impacts or excessive vibrations can also cause the suspension / steering system to lose proper alignment.
* Misaligned front suspension and steering system will cause improper steering (inaccurate self centering of the steering wheel, vehicle not going straight when the steering wheel is straight, excessive tyre wear, etc.).
* Misaligned front suspension and steering system can also cause '''[[Death Wobble|Death wobble]]'''.
* In case of wheel misalignment, wheel re-alignment has to be performed in a professional workshop.
* Read the chapter '''[[Death Wobble#Wheel alignment|Wheel alignment]]''' in the Death Wobble wiki article for some details about the process.

=== Types of wheel damages and repairs ===

==== Scratches ====

* Wheels can get scratched, causing steel wheel to rust and alloy ones to lose appeal.
* However, scratches do not present structural damage, so they are not given much attention in this article.

==== Bents ====

* The mildest (and most often) type of structural wheel damage is a '''b'''ent.
* Bents cause the wheels to become warped, and warped wheels cause rotational disbalance.
* Rotational wheel+tyre assembly disbalance is one of the most common causes of the '''[[Death Wobble]]''' phenomenon.
* It is not always possible to detect a warped wheel, even to the trained eyes. Professional measurement machinery is sometimes necessary.
* In many cases of warped wheels, wheel+tyre assembly balancing measures can not compensate for the bent(s) - the distortions have to be remedied first.
* Most ordinary wheel balancing machines can't even detect the warps, because most of them measure the disbalance in only one plane of motion (longitudinal), and not the transverse "jerking" forces.
* Such machines would complete the balancing process on a warped wheel just fine, and everything would appear to be perfectly balanced (according to the measurements of those machines).
* In reality, the wheel still (sometimes invisibly) wobbles from side to side while rotating.
* There are specialized workshops and machines which can detect and correct the wheel bents, and therefore straighten the wheels (both the steel and alloy ones).
* Only after those wheel straightening measures are applied, it makes sense to perform wheel+tyre assembly balancing.

==== Dents ====

* The medium type of structural wheel damage is a '''d'''ent.
* Dents are usually obviously visible (if you care to look).
* You should occasionally check your wheels for dents, scratches and mud/grit deposits from the inner side (the side facing the brake disc / brake drum when the wheel is mounted).
* A significant dent on a rim will usually be instantly noticeable, because it will allow the air to leak out from the tyre faster than you can fart when you least expect to.
* Dents have a higher tendency to appear on steel wheels than on alloy wheels.
* Dents on steel wheels are typically quite easy to repair.
* Dents on alloy wheels are typically relatively difficult to repair (but more or less possible for sufficiently qualified and equipped servicemen).
* After a wheel dent is repaired, the wheel should definitely be checked for distortions throughout (see the preceding chapter).

==== Cracks ====

* The most extreme type of structural damage is a cracked or shattered wheel.
* Steel wheels rarely, if ever, crack or shatter - they usually crunch.
* Alloy wheels are more susceptible to cracking or shattering.
* The required force to cause an alloy wheel to crack or shatter is usually quite extreme (if good quality wheels are used).
* Some specialized workshops can even mend (patch up) cracked and/or shattered wheels, even in most extreme cases - a wheel is brought to them as a collection of dozen pieces in a bag, and returned like it once used to be - at least visually.
* The answer to the question "whether a mended cracked or shattered wheel will structurally be able to perform its intended duty (and be without any uncorrectable distortions)" is for you to ''discover''.
* In this situation, you might be better off to buy a Land Rover ''Discovery'' (but without cracked wheels).

=== Additional considerations ===

==== Importance of tyre profile ====

* The risk for any of these wheel damage types generally increases with lower profile tyres, and vice versa (less risk with higher profile tyres).
* Reason 1: With lower profile tyres, wheels are closer to the ground, and smaller rocks can reach them.
* Reason 2: With lower profile tyres, there is much less "cushioning" (damping) capacity in tyre's sidewalls when they hit a pothole, curb or a rock, leaving it on the rigid wheel to handle most of the shock.
* Therefore, for general mixed terrain or off road use, '''higher profile''' tyres ("taller" tyres) are always more recommended over lower profile ones.
* Higher profile tyres provide other additional benefits for all terrain use.
* Read the chapter [[#Tyre profiles|"Tyre profiles"]] for more information.
* Now you start to get the idea why the 21st century breed of city-terrain steroid-pumped 4WD vehicles with factory-styled oversized wheels and low profile tyres are utterly absurd in the basic concept.

==== Importance of tyre air pressure ====

* Beware that the risk of wheel damage increases when the tyre air pressure is too high or too low.
* When the tyre air pressure is too high, the tyre will be too stiff, translating most (if not all) of the vibrations and shock loads to the wheel (and further on to suspension and steering components, the rest of the vehicle, up to your kidneys and teeth).
* "Too high" tyre air pressure generally means higher than factory-recommended on-road tyre pressures.
* The only reason to ever use too high tyre air pressures is if you want to cure your stone kidney disease.
* When the tyre air pressure is too low, there is not enough air quantity inside to handle/cushion the '''sudden''' shock loads, therefore leaving the wheel as the "first point of impact".
* The "suddeness" of the shock load directly depends on the velocity of the vehicle.
* Therefore, driving with partially deflated tyres is not a problem, as long as vehicle's speed is correspondingly reduced according to the terrain conditions.
* The lower the pressure, the slower the speed!
* Read the chapter [[#Tyre pressures|"Tyre pressures"]] for more information.

== Tyre damages and repairs ==

=== Introduction ===

* Tyres are the most vulnerable part of a vehicle, and they definitely endure the most harshness when the vehicle is driven in all-terrain conditions.
* To appreciate the role and life of your tyres, imagine or try running bare-footed on the same terrain where you drive on.
* Tyres can sustain several types of damage, and not every type is instantly noticeable.

Educate yourself more about tyre punctures and repairs through [https://rma.org/sites/default/files/prp_wallchart1111_0.pdf '''this article'''] from USA's Rubber Manufacturer Association and through [https://www.tireindustry.org/tire-maintenance/tire-repair '''this article and video'''] from the international Tire Industry Association.

=== Types of tyre damages and repairs ===

==== Tread puncture ====

* This is the most well known and classic tyre damage.
* Tread surface, in the context of tread puncture repair, is considered to be the central 3/4s of the side of the tyre which regularly contacts the ground.
* The remaining outer sections of the ground contact area are called "shoulder area".
* For the predominant radial tyres, general tyre industry convention is that this shoulder area falls in the category of "tyre sidewall" considering puncture repair options.
* A tread puncture can happen either as a (more or less) round pierce (for example a nail), or as a cut (for example a large piece of glass).
* Most tread punctures (if not overly large) can be successfully and permanently repaired by professionals in tyre repair workshops.

* For a tread puncture repair to be proper and permanent, the tyre '''must''' be demounted from the wheel first, and the repair performed from the '''inside''' of the tyre.
* The best type of a tread puncture repair is when two methods are combined - a plug (stem) and a patch.
* Both of those repair methods should be performed from the inside of the tyre.
* Applying just a plug or just a patch is not proper, but many "professional" tyre servicemen are lazy and just do one of the two.
* Persuade them to use both (first plug, then patch)! If talking does not work, then money does.
* A plug repair is when the punctured hole or cut is drilled through to clean it, and then a rubber strip (+ a glue cure) is inserted into the hole.
* A patch repair is when a piece of rubber is glued onto the surface, and then "cooked" for a while to vulcanize (fuse) with the surface on which it is applied.

* "Plug type" DIY tyre repair kits exist from infinite number of manufacturers, and they cost only a few dimes.
* They are handy to carry in the trunk, as they can be used for DIY "on the field" repair of tyre tread punctures.
* However, using '''just''' a plug repair from the '''outside''' of the tyre (without demounting it from the wheel first) should be done only in an emergency when no other options are available.
* It should be considered as a temporary measure until you get a first proper opportunity to have the tyre demounted, the old (temporary) plug drilled out, and the tyre properly repaired as described above.

* Using (recently) much advertized aerosol/liquid/gel tyre filler solutions is '''highly''' discouraged!
* Those solutions are typically held in pressurized cans, which you connect to the tyre inflation valve and then spray the aerosol/liquid/gel inside the tyre.
* The solution spreads through the tyre and (in theory) plugs the puncture while you are pumping the tyre up.
* Even if this succeeds, it is strictly a temporary measure just to get you out of the situation.
* In most cases, tyres which have been treated with these liquid fillers can not be properly repaired afterwards.
* Reason: The liquid has hardened all throughout the tyre and made a complete mess, especially regarding balancing. Cleaning all the hardened aerosol/liquid/gel out requires '''a lot''' of labor effort and cost.
* This renders your "temporarily repaired" tyre practically '''permanently ruined'''.

==== Sidewall puncture ====

* Sidewall puncture is the nastiest type of tyre damage.
* Unfortunately, the risk of sidewall punctures is generally the highest when performing all terrain driving.
* A sidewall puncture can happen either as a more or less round pierce (for example a nail), but much more often as a cut (for example a piece of a tree branch sticking out from the ground).
* For the predominant radial tyres, general tyre industry convention is that '''any''' damage in the sidewall area '''can not''' be successfully repaired.

* However, there are tyre repair workshops which can repair sidewall damage on radial tyres, even in extreme cases.
* Those are typically the same workshops which produce remoulded (retreaded) tyres, at the process of repairing a sidewall is in some aspects similar to retreading a tyre.
* The method of repairing tyre "shoulders" and sidewalls is called "section repair".
* In short, the section repair consists of cutting out the damaged area, filling it with special raw rubber, then applying special (reinforced) patches from the inside, together with some special glues, and cooking (vulcanizing) all that with the sidewall for extended period of time, in a very similar process as when retreading a tyre.
* The reinforced patches contain nets of some strong material (kevlar, titanium, etc. or hairs from horse tails) and require special raw rubber made of frog balls, with specially tailored glue made of bird milk or whatever to properly fuse with the tyre.

* Sidewall section repairs are typically applied to heavy duty tyres which are used on tractors, industrial machines and heavy-duty trucks which work in forestry, construction sites, excavation sites etc.
* Sidewall section repairs have proven to be successful on much smaller and lighter tyres used on all-terrain vehicles.
* However, it is (in most cases) highly discouraged to use such tyres on the road - restrict to using them '''off road only'''!
* If you have to venture out on the road, keep the speed or '''under''' cca '''40-50 km/h''' ('''25-30 mph''')!

* General observation of tyre repair workshops (which perform these kinds of repairs) is that AT class and MT class all terrain tyres are much better suited to performing this kind of sidewall puncture repair than ordinary limousine road tyres.
* The reason is that AT class and especially MT class tyres have certain degree of robustness and reinforcements as a part of their overall construction (aiding the infusion of the patch), while ordinary limousine road tyres have barely anything to "cling on to".

* If a tyre sidewall repair fails later on, it usually fails suddenly (instantly) and catastrophically.
* You '''do not''' want that to happen while your velocity is high!
* If a tyre sidewall repair fails later on in a tricky off roading situation (undulated terrain, steep or sloped terrain, rocks, mud, shit, etc.) raising the vehicle to replace the wheel might turn into a grand project on itself.
* "High lift" jacks are typically used to raise the vehicle in these difficult conditions, but Jimnys '''do not''' have suitable lifting points below the factory front and rear bumpers, and barely suitable ones on the sides!

Educate yourself more about tyre section repairs through [http://www.techtirerepairs.com/content/documents/RM-9---Radial-Truck-Sidewall-Repair-w-Mult-Cable-Damage-1.pdf this] and [http://www.moderntiredealer.com/article/311921/knowing-what-not-to-repair this] article.

==== Bulge ====

To be written ...

==== Cuts ====

To be written ...

==== Chips ====

To be written ...

==== Disintegration ====

To be written ...

==== Cracking ====

To be written ...

{{Edited}}
[[Category:FAQ]][[Category:Steering]]

Talk:Tyre selection and usage - best practices

2017-01-18T04:37:42Z

NelsonB: Modifications, sugestions

Tyre selection and usage - best practices

2017-01-18T04:27:24Z

NelsonB:

= Introduction =

[''This entire article is now more or less complete, but there may be further refinements at any time. Therefore, check it out whenever you decide to buy new tyres!'']

One of the most common questions about improving vehicle's all-terrain performance and endurance is "what is the most effective modification to apply to my vehicle?".
Well, using proper tyres, and using them properly, is arguably the most effective vehicle "mod" for all-terrain use.

Notice:
"Most effective" can generally mean in the context of cost, performance, simplicity or endurance. Using '''proper''' tyres '''properly''' can be the most effective "mod" in all of those ways!

This document includes the following topics:
# Choosing a proper tyre type for the desired usage;
# Choosing a tyre size;
# List of various tyre models with remarks;
# Best practices on tyre usage (wheel rotation, wheel balancing, air pressures, rim and tyre repairs);
# Use of tyre chains for snow and mud conditions;
# Special situations and combinations;

= General remarks =

First of all, some basic remarks about using tyres on four wheel drive vehicles:

1. 
Inherent restriction of most four wheel drive transmission systems (Jimny's included) is that the vehicle has to use all four tyres of the same profile (size). Furthermore, all four tyres should be the same model and have a very similar tread depth (even small differences between rotational friction and wheel circumference among wheels can damage the transmission in the long term). This limits the combinations when choosing (buying) tyres.

2. 
The stated restrictions also apply to the spare (5th) tyre, which must not be overlooked! Topic of spare tyre utilization has its own dedicated sub-chapter: [[#Using five identical tyres|Using five identical tyres]].

3. 
Frequent checking (and adjusting) of air pressures is much more important for all-terrain use than for ordinary on-road use, because pressures significantly affect traction as well as the risk of tyre damage (tyres get hotter with low pressures, for example).

4. 
Wheel (dis)balancing is a much more prominent issue for all-terrain use, especially for Jimnys as they are notorious for developing a [[Death Wobble|"death wobble"]] issue. It is a genetic trait derived from their short wheelbase and solid (rigid) front axle suspension design.

5. 
For all-terrain use, higher profile tyres are always preferred against lower profile tyres (a "higher profile" means "taller" tyre). Reasons: higher profile tyres cushion the ride better on all-terrain both for the vehicle and for the passengers, they decrease the chance of rim damage, and they allow better air pressure management. Their only disadvantage is worse performance when the vehicle corners fast in a bend, but it is insensible anyway to do so in a high, narrow, wobbly, jumpy, twitchy vehicle. Therefore, putting oversized rims with thin tyres on a 4WD vehicle is like putting ballet shoes on a village farmer.

= Choosing a proper tyre type for the desired usage =

== Introduction ==

Tyre designs for passenger and light truck vehicles can be (among other ways) designed and built for regular "on road" use (the vast majority of tyre models) or (to an certain extent) for all-terrain use.

The difference between those two design approaches is not just in the tread pattern (traction capability). Another equally important aspect is tyre's robustness (resistance to various types of trauma, which '''regularly''' occurs off the asphalt), which is generally given dedicated design attention for all-terrain tyres (based on tyre's exploitation expectancy). For ordinary road tyres, robustness is barely considered on itself. Also, tyre's adaptability to different weather conditions is also sometimes given more design thought when designing all-terrain tyres.

There is no official standard to differentiate various kinds of all-terrain tyre designs.

There are three "industry categories" of all terrain tyre designs, based on loose practical usage classifications (from "worse" to "best"):
* 1. HT - "Highway Terrain"
* 2. AT - "All Terrain"
* 3. MT - "Mud Terrain"

Tyre manufacturers usually use this classification to position their all-terrain tyre models in their marketing catalogue.

HT tyres generally have the best on-road performance and worst off-road performance of all three categories, while MT tyres generally have the opposite performance characteristics. AT tyres are generally in the middle - being good but not great for both.

Since these are loose classifications, there are "weaker" and "stronger" tyre models in each category, so each tyre model should be precisely evaluated on its own. For example, Dunlop Grandtrek AT20 could be classified either as a "mild AT tyre", or as an "extreme HT tyre" :). Another example is Uniroyal Laredo HD/T, which could be classified either as a "mild MT tyre" or as an "extreme AT tyre".

A special case are retreaded (remoulded, "protect") tyres. Read more about them in the subchapter below.

== HT tyre class ==

* Highway terrain tyres are generally meant to be used predominantly on road, with only slight & light off road excursions (possibly rougher gravel, some grasslands, etc.).
* Their overall tread design and depth is generally quite similar to ordinary road tyres. That means that they generally have equally proficient on-road performance and endurance even for sharp or very fast driving (and similar fuel economy), but almost equally bad all-terrain performance as ordinary road tyres.
* However, having the "terrain" part in their name, HT tyres should be slightly more robust than ordinary road tyres.

Conclusion - for (almost) always on-road driven all terrain vehicles, HT tyres can be an optimal choice if the vehicles are driven sharply or at high speeds. They are always recommended over ordinary on-road tyres for two reasons - they should be more robust and they at least formally "suit" the all-terrain image of the host vehicle.

However, AT tyres are definitely a better choice if proper all terrain driving is even occasionally performed, and/or if the vehicle is not driven fast or sharply.

== AT tyre class ==

* All terrain tyres are generally meant to be used in mixed on-road and all terrain conditions (anywhere between 30% and 70% of time for either).
* They usually have significantly rougher (and a bit deeper) tread design compared to HT and ordinary road tyres.
* They are a performance compromise which is usually hard to achieve.
* They are generally good on-road except for sharp or very fast driving, and generally good off-road except for boggy and/or harsh conditions (deep mud, deep snow, sharp rocks, river crossings ...).
* They are usually significantly more robust than ordinary road tyres.
* They should slightly impact fuel economy.
* They can be a challenge to balance properly.
* Many AT tyres are "all season", which further adds to their "all terrain" value (for example, mountaineers can encounter ice and snow even in June and as early as September).

Conclusion - for all-terrain vehicles which are used for everything - commuting, intercity travel, and various all terrain conditions, AT tyres are the solution. They should not present a jeopardy on the road, and they should be a trusted companion off the road, in the sense of traction and in the sense of reliability.

== MT tyre class ==

* Mud terrain tyres (also called "Maximum Traction") are generally meant to be used predominantly off road, with only slight easy-going on-road excursions.
* They usually have very deep and striking ("tractor looking") tread and sidewall appearance, and very high robustness capability through various reinforcements.
* They excel in boggy and/or harsh conditions (deep mud, deep snow, sharp rocks, tree roots, river crossings, etc.) and offer the best protection against punctures, cuts and chipping.
* However, they are generally noisy on the road, wear faster and present a real jeopardy if not driven slowly and carefully on a wet road and especially on packed snow or ice.
* Also, they usually significantly affect fuel economy. Due to their coarse construction, they can be very hard or impossible to balance properly.

Conclusion - for all-terrain vehicles which rarely touch the asphalt and are used on tough terrain, MT tyres should be the weapon of choice. However, they can be a jeopardy on regular road surfaces and they wear out faster and louder on road. Also, if not balanced entirely, they will cause issues on road.

== Retreaded (remoulded, "protect") tyres ==

A retreaded tyre is a recycled tyre - it is a previously used and worn out tyre, which had its worn tread surface grinded off, and a new tread (which can have completely different pattern from the old one) glued on.

The material of the new tread is specific to the retreading "factory".

Therefore, retreaded tyres are essentially "tyre zombies" - they are old, worn tyre carcasses which have been restitched and brought back to life like Frankenstein.

Retreaded tyres are produced in all kinds of editions and flavors, with their treads typically mimicking a well known brand name tread pattern. They can mimic any tread pattern, either of slick and smooth road tyres, summer or winter tread designs, as well as heavy-duty AT, MT or even more extreme agricultural and industrial tread patterns. They can also be made with a custom tread design of any appearance that you can imagine.

So, retreaded tyres are great because they are very cheap, ecological, and because there is a wide and colorful choice of tread patterns, especially the extreme traction ones.

But there is a cost to pay. Read on.

Bear in mind - if a tread appears the same like from a brand name tyre model, it does not mean that the materials and compositions of the tread are the same.

Also, you hardly ever know which actual tyres were used for resurrection. For all-terrain duty, tyre sidewalls' strength and robustness are equally important as the tread pattern.

There are also horror stories of retreaded tyres failing catastrophically during high speed driving - the tread layer actually glues off from the tyre carcass. The consequences don't look pretty from any angle of view.

Last, but not least, in some countries an agressive tread remoulded tyre could render am enviromental fine in some backcountry roads.

Beware that Jimnys (as all vehicles with solid front axles) are highly susceptible to developing a "death wobble" issue produced by disbalance or play in their front suspension (see [[Death Wobble]] wiki article). Improper wheel balance is highly likely to trigger it. Retreaded tyres are notorious for being hard or impossible to balance. So beware!

[https://docs.google.com/spreadsheets/d/1-1RXKtrBykdw7V9X1WX3jLXpSdygKb8ji3y1WJZhR0g/pubhtml '''Here'''] is a document (''made by forum user [https://www.bigjimny.com/index.php/forum/profile?view=user&userid=16580 Bosanek]'') which summarises all arguments FOR and AGAINST using retreaded tyres.

= Choosing tyre size =

== Reasons and benefits ==

Why would you want to change your tyre size?

Well, for all terrain vehicles, the usual strive is to increase ground clearance. Increasing wheel diameter by increasing tyre profile (the second number in tyre size marking) is the most effective way to achieve this. It lifts the entire vehicle (including the axles!), and is dead simple to do for mild increases.

There are additional advantages of increasing the tyre profile ("tyre height") - as mentioned in the [[#General remarks|"General remarks"]] chapter.

Note: When a wheel diameter is changed by a certain amount, the vehicle's (and the axles') ground clearance will change by only half as much (by the amount of wheel's radius change) - basic school geometry explains why.

== Issues and risks ==

'''However, increasing the wheel circumference/radius incurs the following technical issues:'''
# The vehicle will accelerate harder / slower and will move faster downhill on engine braking (in any gear);
# Transmission will have a heavier duty to perform, leading to premature wear in the long term;
# Fuel economy can be slightly decreased (because of harder acceleration);
# Speedometer and tachometer measurement will change as much as the circumference has changed;
# Larger tyres might not fit - they might rub on the bodywork when the wheels are turning or the suspension is compressed on uneven terrain;
# The larger spare tyre might not fit in its spare position (contact with some vehicle body parts) and/or in its case/cover;
# Using snow/mud chains can be risky or impossible, because of (much) less available clearance between the wheels and the surrounding bodywork and mechanical components. However, 4WD vehicles might need snow/mud chains only on steep icy terrain, or for plowing very deep snow. A 4WD vehichle with AT tyres also could benefit of chains in deep soft muddy terrain.

The extent / severity of these issues highly depends on how much the wheel radius has been increased. They should be negligible to slight at most, if you stay roughly within +-3% of the factory size.

Using too wide tyres also induces some of these issues and risks.

'''Some of these technical issues can be (and usually have to be) remedied in case of significant tyre size increases:'''
# Impact on vehicle's acceleration and engine braking can be remedied by altering the transmission gears ("regearing").
# Regearing the transmission will also remedy the load on some parts of the transmission, but some parts, like the wheel bearings for example, will remain under heavier duty;
# Tyres can be made to fit properly by two methods - firstly by lifting the vehicle's body or suspension and/or secondly (usually irreversibly) altering the bodywork (trimming the wheel arches, inner arch linings, etc.), the extent of which highly depends on tyre size;
# In Jimny's case, the larger spare tyre can be made to fit to the tailgate by installing a spacer on the tyre holder, but the spare tyre vinyl cover or hard spare tyre case has to be custom-made (if badly needed);
#Very wide tyres, significantly increases the drag force when pulling a bogged vehicle from depp mud.

Some of the mentioned remedies can be quite expensive to apply, and might also imply further modifications.
For example, higher suspension lifts require modified radius arm bushes, brake hoses, propeller shafts, adding wheel spacers, buying a new loan at the bank ....

Note: using non-factory tyre size might be illegal or require some vehicle recertification, depending on country or region.

= Jimny factory tyre size and approved sizes =

The factory tyre size on all Jimnys is '''205 / 70 / R15'''. Exceptions are some JDMs (Japanese domestic models) and some Brazilian models (215 / 75 R15).

According to some South African and Australian forums (example: [http://www.4x4community.co.za/forum/showthread.php/67086-Approved-Jimny-tires this forum topic]), their local Suzuki dealers' official policy is to allow +-3% variation in wheel diameter. Therefore, if your Jimny is under warranty (or you want to be mechanically moral), +-3% is your expansion border.

= Compatible & interesting tyre sizes for Jimny rims =

== Quick and simple decision ==

The three most popular, non-extreme size upgrades are to:
# '''205 / 75 / R15''' - (ground clearance and tyre's sidewall height increase by cca. '''10 mm''')
# '''195 / 80 / R15''' - (ground clearance and tyre's sidewall height increase by cca. '''13 mm''')
# '''215 / 75 / R15''' - (ground clearance and tyre's sidewall height increase by cca. '''18 mm''')

However, they '''may''' impose certain risks of collisions between tyres and the vehicle body in some vehicle configurations. That mostly depends if the vehicle has 2nd gen. front bumper or not, if it has front mudflaps or not, if wheel spacers are used, etc. Brazilian "HR" and "for Sport" versions models with 215 75 R15 came with an aprox. 5cm body spacers. The risk is the lowest with the first size in the list, and the highest with the third size in the list.

They will also introduce certain deviations in vehicle's driving characteristics (road handling, acceleration, top speed, engine braking, transmission's stress). However, those deviations range from "negligible" to "small". The first size in the list is the least deviant, as it provides the smallest diameter change, while also keeping the same tyre width.

Bear in mind that while the first size '''might''' be allowed by Suzuki (depending on company's regional policy), the second and third sizes are definitely not allowed by Suzuki(regional excemptions apply). Also bear in mind that ANY tyre sizes apart from those which are strictly specified in vehicle's handbook are prohibited in certain countries!

'''Warning:''' MT class tyres, and especially "remoulded" (retreaded) tyres, typically deviate significantly from their theoretical sizes (they tend to be quite larger)!

=== Regarding "tyre vs. vehicle body" collision risks ===

Sizes 205 / 75 / R15 and 195 / 80 / R15 generally have no risks of collisions with the vehicle's body, with two exceptions:
* If you have a 2nd gen. front bumper (see below), you might have to straighten it if it is sagged, or trim it just slightly (invisibly) on the bottom (simple job with a grinding tool).
* If you have front mud flaps, you might have to trim a plastic spacer behind them by approx 10-15 mm (which is easy to dismount and mount).

Size 215 / 75 / R15 could be more problematic:
* It may require some trimming of the bottom of the front bumper, especially if it is a 2nd gen. bumper.
* Front mudflaps will probably need to be removed.
* The spare tyre might contact with the rear bumper.
* Wheel arch trimming is generally not needed, except if wheel spacers are used without a lift.
* Brazilian versions that came with 215 75 R15 from the fabric, had an aproximate 50mm body lift. The "for sport" version, also had a minimalist front bumper with increased tyre clearance and higher approach angle.

This was a quick and simple guide to the issue of tyre sizes.

== Thorough consideration ==

On the other hand, if you want to dig neck deep into the issue of tyre sizes, study [https://docs.google.com/spreadsheets/d/1qwxmEIQ98WjkWoMsE49TNWHG4xq8P6C0cQZJcriiiL8/pubhtml?gid=0&single=true '''this table'''] on Jimny-compatible tyre sizes, which was made by forum user [https://www.bigjimny.com/index.php/forum/profile?view=user&userid=16580 Bosanek].

That table shows all compatible & interesting tyre sizes which fit on Jimny's stock steel and alloy rims. It also contains many compiled remarks of risks and issues for each non-stock tyre size. Those issues are rarely taken into consideration until it is too late!

The availability of different tyre models in desired tyre size will vary significantly. Not all tyres are manufactured in every listed tyre size.

As it is evident from the table, even if you choose to stay within Suzuki's alleged 3% allowed wheel diameter increase, there are several tyre profiles which can be used to achieve the goal of higher ground clearance.
It is preferred to achieve the goal by increasing sidewall height (second number in tyre profile sizing code) instead of altering tyre width (first number in tyre profile sizing code). Maximum "gain" is achieved if both are increased at the same time.

= Tyre models in Jimny-compatible sizes =

There is a wide variety of HT, AT and MT class tyre models which are available in Jimny-compatible sizes. It would be a pity to use an ordinary limousine road tyre instead!

[https://docs.google.com/spreadsheets/d/1jFMegEyyC1dJex8oPji3h8ASGHHONHgX44albDzM0qg/pubhtml?gid=1691702446&single=true '''This table'''] (''made by forum user [https://www.bigjimny.com/index.php/forum/profile?view=user&userid=16580 Bosanek]'') contains the list of all brand-name HT, AT and MT tyres which he has found on the worldwide market.

In addition to the list of tyre models, that table also contains the availability of each tyre model in most popular Jimny-compatible sizes!

''Note: A lot of time has been spent populating that table, and adding custom remarks there. The table is still incomplete in some details, but will be updated from time to time. The sizing availability is the most incomplete, as it takes a lot of investigation to fill the required data for each tyre model.''

Therefore, once you settle on your desired tyre size, now you can browse through tyre models and choose the one which is available in that size and suits your criteria the best.

Note: Not all of those tyre models in the list are available in sizes which are compatible for Jimny.

== User experiences with certain tyre models ==

Here are four AT tyre models with which Jimny owners have had great or good experiences with:
* Goodyear Wrangler AT/SA+
* General Grabber AT (not AT2!)
* Continental ContiCrossContact AT
* BF Goodrich AT/KO

All three of those models have proven themselves as being very good on-road in any time of year, while also proving to be rather versatile off road.

Also, General has recently (09/2016) released model '''AT3''', which looks very interesting indeed. Avoid the model AT2, it is very old and deprecated one!

If you insist on heavy-duty off-road performance but still want to retain '''some''' on-road credibility, there are three MT class tyre models with which Jimny owners have been relatively satisfied with:
* Bfgoodrich Mud-Terrain T/A KM2
* Hankook Dynapro MT (RT03)
* Kumho Road Venture KL71
* [http://www.maxxis.co.uk/catalog/tyre-3-21-trepador-radial-m8060#sizes Maxxis Trepador M8060] (Martin Lines comment: I have found these particularly good on a standard Jimny)

There are other good AT and MT tyre brands and models of course.

= Spare wheel and tyre usage =

== Introduction ==

All proper all terrain vehicles, like Jimny, come with a full size matching spare wheel, which is the same as the other four wheels.

That is for a reason. That spare wheel and tyre are not meant to be just carried around and sit idle all the time.

For all terrain vehicles, spare wheel is not a fashion accessory nor a "dead cargo". It is an important operational element of the vehicle, as well as an important safety device.

Therefore, a spare wheel and tyre must not be overlooked.
Otherwise there are multiple risks of staying stranded in the event of the simplest tyre puncture, or even damaging vehicle's transmission in the event that the spare wheel does indeed have to be used!

The spare wheel and tyre should be actively and periodically rotated together with the other four wheels and tyres. In other words, the 5th wheel and tyre should play an equal role and importance as the other four wheels and tyres.

However, there are some rules and restrictions - read more in the following subchapters.

== Using five identical tyres ==

Buy and use five same (identical) tyres! The spare tyre should not sit idle all the time! That is even written in Jimny's owner manual.

The spare tyre should be actively rotated with the other four. In case of an all-terrain vehicle like the Jimny, that gives you so much benefits, and only one downside - you pay 25% more at once when buying the tyre set.

[https://docs.google.com/spreadsheets/d/1svFOPe-Z1xS2BbiYvr3jQbAortqZevZy74VC9wdo9Dk/pubhtml '''Here'''] is a document (''made by forum user [https://www.bigjimny.com/index.php/forum/profile?view=user&userid=16580 Bosanek]'') which shows the rotation scheme, and also lists "FOR" and "AGAINST" reasons to actively use all five identical tyres in a 5-tyre rotation scheme.

It is a good practice to rotate the tyres with every engine oil change. If you recently bought a set of four new identical tyres (they have not got worn more than 1-2 mm at most), you still have time to buy the fifth one (you don't need it yet, until the first rotation).

'''Warning:''' If you have a hard or soft spare wheel cover, you won't be able to use it with a spare tyre which is larger than the stock size.

'''Note:''' Five-tyre rotation scheme is '''not''' practical with tyres which have directional (uni-directional, asymmetric) treads, because each such tyre must be used on only one side of the vehicle for which it was made for. Unidirectional tyres typically have a "Rotation" with arrow mark on their sidewalls, indicating proper orientation. Therefore, when using five tyres, always use non-directional (bi-directional, symmetrical) tyres. Luckily, most HT, AT and MT tyre models have symmetrical treads, but there are exceptions. Beware of this!

== Using a non-matching spare tyre ==

Using (periodically rotating) a matching spare tyre together with the other four tyres is strongly recommended, as per the above subchapter '''[[#Using five identical tyres|"using five identical tyres"]]'''.

However, if, for whatever reason, a non-matching spare tyre has to be used on a 4WD vehicle, special caution has to be applied in order to avoid expensive transmission damage!

This subchapter is a guide what to do in this unfortunate event.

Note: ''To avoid getting into this situation in the first place (and to reap many additional benefits along the way), read the preceding subchapter about [[#Using five identical tyres|"using five identical tyres"]]''.

First of all, a ''non-matching'' tyre in this context means any of the following:
* Different tyre size (width or height) than the other four tyres;
* Different tyre model than the other four tyres;
* Tyre's tread depth more than 1 mm or 2 mm different than the tread depth of the other four tyres;

The cause of the issue with using a non-matching spare tyre is that any 4WD transmission with a non-existing center differential (or when a center differential is locked) expects the same rotational speed and rotational friction from all four wheels. If that is not the case, the gears and shafts of the transmission literally tension and wind up because of the discrepancies caused by a non-matching wheel. If the tension and wind up become sufficiently high, something in the transmission '''will''' break. With a non-matching spare wheel in the game, the breaking point could be just a few wheel turns away!

=== Installation position ===

With part-time 4WD vehicles like the Jimny, the non-matching spare wheel should always be used on the front axle. The reason is that the front wheels are disconnected from the entire transmission when the vehicle is in 2WD and 2WD-L mode, and therefore using a smaller wheel does not impact the transmission then.

So, if one of your front tyres get punctured, just replace that wheel with your non-matching spare wheel and tyre.

However, if one of your rear tyres gets punctured, the procedure would be:
# Remove the punctured rear wheel;
# Remove one good front wheel;
# Install that front wheel in the place of the punctured rear wheel;
# Install the spare non-matching wheel in the place of the removed front wheel.

That's a lot of work if it's hot, cold, wet, dusty, raining, windy or night time! But it is the only proper way.

Now, when the non-matching spare tyre is on your front axle, as long as you don't engage 4WD, you should be fine. So, do your best to get to the nearest tyre repair workshop strictly in 2WD mode. If you have manually operating front wheel hubs, make sure that they are disengaged all the time.

=== Using 4WD mode with a non-matching spare tyre ===

If you get a puncture in the middle of offroading where you need 4WD to get to civilization, you are in trouble.

After installing the spare non-matching wheel on the front axle per the above instructions, constrain the use of 4WD only when it is absolutely necessary. Disengage 4WD as soon as it is not strictly necessary, and engage it later when necessary again, and so on. If you have manually operating front wheel hubs, you have to engage and disengage them every time in sync with engaging and disengaging 4WD.

Alternatively, using 2WD-L mode would be safe in regards of the issue of non-matching spare tyre, and it might provide enough aid to get you trough difficult sections instead of using 4WD. However, Jimnys have to be modified first in order to enable 2WD-L transmission mode. See the chapter [[2WD-L transmission mode]].

While 4WD is used, the size or friction discrepancy on one wheel will cause '''constant''' transmission wind up as long as the vehicle is moving in 4WD. However, as long as 4WD is used on rather slippery ground (snow, mud, very loose gravel), the wind up should be able to constantly relieve itself, without harmful consequences.
In other words, one wheel will have to ''continously'' "underslip" in order to compensate for the discrepancy. Only very slippery ground can enable that.

The most difficult situation would be with rather rocky or bumpy '''dry''' road, where you usually need to use 4WD-L 1st gear to pass slowly. Because the road is '''dry and/or rather solid''', there is not enough chance for the transmission to relieve itself of the continuous discrepancy (for a wheel to continuously underslip), and transmission damage is quite likely!

Therefore, if you have to use a non-matching spare tyre on a dry rocky or bumpy road, the best option is 2WD-L 1st gear.
However, if your Jimny is not modified to have 2WD-L mode, it might be better to use 2WD 1st gear instead of 4WD-L 1st gear.

That means you have to go through faster, or drive "improperly" by riding the clutch and/or the brakes. It is the driver's decision whether to risk the damage to the suspension done by going faster through rocks and bumps, or to the clutch if riding it, or on the other hand, to risk damage to the transmission in 4WD-L mode.

= Tyre pressures =

Learn and use the skills of tyre pressure management.

Changing your tyre pressures to suit the (off)road conditions is the '''most effective''' vehicle mod ever!

The benefit is not just for improved traction, but also for improved ride comfort and reduced vehicle stress!

In general terms, reducing tyre pressure by 20-30% from stock on-road pressure is the operating norm for hard (rough) gravel and general off-road conditions. For deep mud, deep snow, sand and other boggy conditions, even more pressure reduction can be used (but with caution).

So, for a Jimny, the stock tyre pressure is 1,6 bar (23 PSI) front and 1,8 bar (26 PSI) rear (some people even it to 1,7 bar on all four tyres).

When driving on gravel roads or general off road, it is completely fine (and even advisable) to reduce the tyre pressure by 25-30% to 1,25-1,15 bar (17 - 18 PSI) - the difference in ride quality is '''astonishing''', while the traction is significantly improved.

'''Warning:''' When tyre pressures are reduced, vehicle's top speed should be limited to approx '''50 km/h''' (~ 30 mph) on tarmac roads, or ~ '''40 km/h''' (~ 20 mph) on gravel roads. Otherwise, the tyres might overheat and disintegrate prematurely!

It is compulsory to carry a good quality tyre pressure measurement tool, and very desirable to have your own 12V air compressor.

You can inflate your tyres at gas stations (their equipment is much quicker than your own compressor), but never trust the pressure measurement instruments at gas stations, as they can be '''wildly''' inaccurate! Trusting that a publicly (ab)used pressure measurement instrument at a gas station is accurate is like trusting that a prostitute has no STD. [I really suggest a change here. In some places, like in some Urugay countryside, very old (read, hystoric) pressure instruments at public gas station work surprinsingly well, because are well treated by the public}.

= Wheel balancing =

Jimnys, as all vehicles with solid front axle suspensions, are susceptible of developing a "death wobble" vibration at a certain speed range.

(''Read more about death wobble in '''[[Death Wobble]]''' wiki article'').

Since wheel disbalance can easily cause death wobble, you need to take additional considerations in order to balance your wheels properly.

You can educate yourself about wheel balancing issues at the dedicated chapter "Wheel balancing" of the above mentioned death wobble wiki page: '''[[Death Wobble#Wheel balancing|Wheel balancing]]'''

{{Edited}}
[[Category:FAQ]][[Category:Steering]]

Talk:Tyre selection and usage - best practices

2017-01-16T19:16:38Z

NelsonB: going forward

Talk:Tyre selection and usage - best practices

2017-01-16T03:43:02Z

NelsonB: wiki UK oriented, or global oriented approach?