Re:Calibration after tyre change?

Hi,

Will get my brand new Jimny in a few weeks, want to swap default Dunlop 195/80R15 with some BFG 215/75/R15 tyres. Dealer says if I do so they need to 'calibrate' the car again (at a cost of course). Other than adjusting the "wheel-rpm-to-speedometer-ratio" (if that is at all possible) because the circumference of the BFG is 1.5% larger than that of the Dunlop there's nothing much I think there's actually do be done.

Is this some BS from the dealer to get some more money out of me or is this genuine?

Cheers

Answer to my own question above:

I just got a call from the dealer and they explained the calibration has to do with the cameras for the automatic braking, they say the car needs to be on a jig and those camera recallibrated at some target, all because the car is now higher with the larger wheels.

What I personally think:

Since the BFG tyre is 1.0 cm higher than the Dunlop, it raises the car by half of that which is a mere 0.5 cm. In my opinion this 0.5 cm is utterly insignificant compared to the influence of the loading of the car: weight of occupants and luggage, roof tent and whatnot.

They charge $200 NZD for it. I say it's money thrown away, especially since I don't like the auto-braking feature to begin with.

Also: the one thing they DON'T change is the speedometer-ratio, which is the one thing I would have found logical. So my speedometer will always show 1.5% less then actual speed (but then so will my odometer).

So I say it's BS and

I think most people that have fitted 40 and 50 mm lifts have managed fine with no problems without have the cameras recalibrated.

I have had no problems.

Nah, it's got nothing to do with the law.

Eventually the head of the workshop (the guy who called me back) even said that if I switch off the auto braking feature than of course it doesn't make a difference anyway. It's just something that allegedly Suzuki recommends and the dealer will be all too happy to cash the extra $200 for this 'calibration'.

It's really silly as yes, a raise of 0.5 cm makes a (insignificant) difference to the angle at which the cameras see traffic in front of the car but the weight in front or back or roof wil have much bigger influence.

In all practicality it's a non-issue.

We were discussing the safari edition on here a few weeks ago and the tyre size you are changing to is what they provide that edition with as standard, so you're not doing anything out of the ordinary by Suzuki NZs own standards.

"With a nod to its 50-year lineage, the Jimny Safari packs a punch of retro style and leading-edge performance. Elevated on Maxxis AT980 all-terrain tyres"

We do not have that on jimnies gen4 here in South Africa.

My point is on lift of 40 or 50mm I can maybe understand re calibration, but 10mm, can it really have such a difference of car computor calculations?

BUT

If not re-calibrated.
(example is extreme, and dont qoute my figures here- purely for illustration purposes of a point.)

Computor can calculate to bring vehicle to a stop in e.g. 5.13meter normally (computed and actual. Now it calculate it to bring vehicle to stop in 5.13meter computed but actual will be 5.25meters. Can that distance make a difference between life and death.

If that little extra distance cause a death, are you willing to live with fact that you know the jimny could have stopped in 5.13 meter and the some iron piece/rod that caused the fatal injury/ death, would not have penetrated that extra 10mm into a scull if the car was calibtrated.

It is 1 out of million change that it could happen, so highly unlikely, but it is a possibility.

I dont know your laws in your country.
We all make decisions like these everyday and we always live with the consequences.

Only you can really say/decide if you want it re-calibrated or not and then live with that decision.






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wrote:

We do not have that on jimnies gen4 here in South Africa.

My point is on lift of 40 or 50mm I can maybe understand re calibration, but 10mm, can it really have such a difference of car computor calculations?

BUT

If not re-calibrated.
(example is extreme, and dont qoute my figures here- purely for illustration purposes of a point.)

Computor can calculate to bring vehicle to a stop in e.g. 5.13meter normally (computed and actual. Now it calculate it to bring vehicle to stop in 5.13meter computed but actual will be 5.25meters. Can that distance make a difference between life and death.

If that little extra distance cause a death, are you willing to live with fact that you know the jimny could have stopped in 5.13 meter and the some iron piece/rod that caused the fatal injury/ death, would not have penetrated that extra 10mm into a scull if the car was calibtrated.

It is 1 out of million change that it could happen, so highly unlikely, but it is a possibility.

I dont know your laws in your country.
We all make decisions like these everyday and we always live with the consequences.

Only you can really say/decide if you want it re-calibrated or not and then live with that decision.






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I don't think the vehicle has a ride height sensor nor does it know the position of the suspension compression. So I'm not sure how this could really be an issue. As the height of the camera will depend on many things and it will move up and down relative to anything it can see, as the suspension extends or compresses or the front of the vehicle is in a dip or on a rise compared to the rear. Tyre pressures could also impact this.

wrote:

The 4 does have a ride height sensor which is primarily for the headlamps but it's likely also used for other things like collision avoidance.

Isn't it only for one axle (rear) though? It'd know pitch, but not actual height. No idea how it works, just taking a guess.

Lambert wrote: The 4 does have a ride height sensor which is primarily for the headlamps but it's likely also used for other things like collision avoidance.

Lambert, Yes, to be honest i have no idea as we dont have the collision avoidence system.

I do know the on on the back axle adjust headlights as I had to add longer one after I did 50mm lift.

My point largely was on collision avoidance system and sure cameras angle pitch and computor somehow work out some distance somehow.

Glad we do not have collision avoidance system added here in South Africa. 1st world things not always gel with 3rd world counties infrastructure.


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wrote:

Answer to my own question above:

Since the BFG tyre is 1.0 cm higher than the Dunlop, it raises the car by half of that which is a mere 0.5 cm. 

So I say it's BS and

Just a suggestion for your consideration - what's the "tread depth" like - what is the difference in vehicle height between a brand new tire and that same tire when it is at the minimum safe tread depth?  I'm estimating at least 5~6 mm, and I can't see Suzuki recommending a recalibration because the tires are worn, or owners being willing to pay for it.

I'm agreeing with you, there's some BS being spread there.

I just ordered 215/75R15 General Grabber A/TX for my 2021, it'll be a while before I actually have them, and a quick check of the website shows tread depth as 14 with no unit specified, if that is 14mm, then I would need to recalibrate between tire changes - good thing my car doesn't have EAB.