JB74 3-Door — Lightweight OEM+ Build Feedback wanted

Snowbum wrote:

• mild off-road touring
• [...[
• Full-size matching spare

In my opinion you won't need a full spare. The punctures I have endured have all been caused by sharp metal objects (nails, screws etc.) caught on paved roads. Also, experimenting with different tyres can become addictive so you would save money by not having to replace the 5th each time. A weight saving there too.

I use HT tyres in summer time and so far the limitations I have experienced have been down to ground clearance of the vehicle.

The Coil Spring wrote:

In my opinion you won't need a full spare.

I don't know which country the discussion starter is in or where he plans to go touring, but, in my corner of the world, where "off road" means limited cellular coverage (and by the way, being "on road" doesn't guarantee cell service), I would strongly recommend, a full sized spare, a tyre repair kit, and some way to re-inflate the repaired tyre.

Your punctures might have been caused by sharp objects on paved roads, but the question needs to be asked, what did you do without a spare, call for road side assistance?  That's not always an option, and even when it is, what is the "lost time" like?  Now take yourself "off road", does road side assistance even come out to where you are, and how much longer will that take?

Based on my experience with rental cars in the US (the only time I've used road side assistance), I can change a flat tyre & be on my way, long before road side assistance arrives on the scene.  Even on paved roads, I'll take a full sized spare.

Someone's going to ask, why a spare and a repair kit, so here's the answer, have you ever tried to change a wheel with the vehicle not on level ground?  Punctures don't always happen where it's safe and/or convenient to change a wheel.

Fordem, let me clarify. I meant that the original Jimny spare will do. It is not essential to have a spare wheel full identical to the other four. One of the aims is to keep weight down and I assume that the suggested wheels will be heavier than the Jimny originals.

But, I agree with you that even the fanciest spare wheel in the world can be pointless if one has no repair kit and means to inflate.

I still don't agree, and I think the issue I am facing is getting you to understand that the distances involved MUST be taken into consideration.

It has been surmised that the discussion starter might be in Australia and looking to get into outback touring, I'm in the Amazonian rainforest , the similarity between the two is both are huge tracts of land with relatively low population counts, in both cases, there is a need for 'self sufficiency", the distance between the point where you get a flat tyre and where you can get said flat tyre repaired/replaced can be a few hundred miles.

Let's look specifically at fitting larger road wheels and keeping a stock spare in the most simplistic fashion possible.

If you take a conventional 2WD car with an open differential and fit different sized tyres to the drive axle, you are forcing the differential pinion gears to rotate continuously, they were not designed for this and typically they have neither bearings nor bushings, it's usually a cast steel gear riding on a hardened steel pin. Under normal circumstances, these gears would rotate only when the vehicle is turning a corner. Instead you're forcing these gears to rotate continuously for potentially a few hundred miles. Drive train damage becomes not just possible, but probable.

The situation with a 4WD will differ, depending on the design of the 4WD system, but a Jimny with AllGrip Pro uses the same type of open differential.

A lot more difficult to quantify is the impact of the different rotational speeds of the tyres on the ESP system, the point at which it will decide that one drive wheel is turning fast enough relative to the others is going to be dictated by the difference in diameter, but if it happens, the ESP may view that wheel as having less traction and engage the BLD (Brake Limited slip Differential) function - consider the impact of applying the brake to a single front wheel whilst the car is in motion, that car is going to pull in the direction of the braked wheel, on gravel, even at a reasonable speed, I'd rather not see it happen.

If you're relatively close to civilization, you can chance it, but if you're not, you need to evaluate the risk and decide accordingly.

 

Here's the last flat tyre I had on the trail, no, this is not a Jimny, yes, I have been known to take two full sized spares depending on my destination, and yes, I have had multiple flats on the same trip and driven out on a tyre stuffed with grass.

The last time I had to stuff a tyre with grass - it is not easy - the grass caught fire within 3 miles or so due to friction within the tyre (I assume).

Roger