Tire Height

[dsp300c]

Gonna change tires again and I remember a thread talking about tire height and once you under or over a certain amount in tire height difference, the car could throw codes and act weird. What is the height difference you want to stay above? Keep it at least 1

[ViperGeorge]

Gonna change tires again and I remember a thread talking about tire height and once you under or over a certain amount in tire height difference, the car could throw codes and act weird. What is the height difference you want to stay above? Keep it at least 1

I was one of the first to post about the issue with my 2015 TA 2.0 while running 315/30/18 Hoosiers up front and 345/30/19s in rear. I was unable to find out what the threshold was for causing the codes and I asked some SRT engineers about it. They simply told me that the different tire heights would effect Stability Control, Traction Control, and ABS. The later being harder to feel. Changes in tire height could cause the Traction Control to believe one axle is slipping relative to the other and cause it to kick in. This is what was happening to my 15. The traction control light would flash on the dash and the car would not go.

You can eliminate this problem by turning the system off or putting it in track mode (both of which turn Traction Control off) but I was told that you could not do anything as to the impact a changed tire height could have on the ABS system. I can't say I ever felt a difference in ABS but then maybe I just don't brake hard enough.

With the tuning that is possible now with the Gen 5 I wonder if there is a way of programming different tire sizes into the car. You can do this with Jeeps (I run 35s on a 2015 Rubicon but others run 37s,41s, or even bigger). The tire size can be configured so that the speedometer is still correct and I've never had an issue with traction control. Then again the Jeep does not run a staggered tire setup.

[dsp300c]

I've had 3 different tire setups with 3 different height difference from front to back. So far I haven't run into any issues with my setup below.


2.4" OEM P Zero on 18/19 on SW2
2.2" Toyo R888 295/30/18 and 345/30/19 on SW2
1.2" Toyo T1R on 275/30/19 and 345/25/20 aftermarket wheels


Below are the tire setups I'm looking at because I want to go back to the Toyo R888R and I don't have much sizing options being 19/20 and I don't plan on selling my wheels b/c I love them. 285 could work but afraid the .8" difference being below 1" could cause issues. I think the 295 would be best but I would prefer the 305 b/c the height difference is only 1.4" Wanting to keep around 1.2" difference because the way the car sits now is really good. I'm not wanting the 275 below because the 275 I have now to me isn't wide enough for the 10" rim and the tire curves at the top even though the height difference is closer at 1.1".

All of these are Toyo R888R with the rear tire being a 325/30/20

275/35/19 would have 1.1" difference
285/35/19 would have .8" difference
295/30/19 would have 1.7" difference
305/30/19 would have 1.4" difference


Attached a pic of my spreadsheet b/c I'm OCD and it may make it easier to see.

Capture.PNG

[JonB ~ PartsRack]

I was one of the first to post about the issue with my 2015 TA 2.0............... I can't say I ever felt a difference in ABS but then maybe I just don't brake hard enough.

HA-HA.

[threatta]

What do y'all do about differences related to speedometer and odometer? Do you have to re-calibrate so you don't get different readings that could show wrong speeds and mileage? More specifically what have people done for ACR's other than Khumo's and same question relative speedometer/odometer?

[ViperGeorge]

I've had 3 different tire setups with 3 different height difference from front to back. So far I haven't run into any issues with my setup below.


2.4" OEM P Zero on 18/19 on SW2
2.2" Toyo R888 295/30/18 and 345/30/19 on SW2
1.2" Toyo T1R on 275/30/19 and 345/25/20 aftermarket wheels


Below are the tire setups I'm looking at because I want to go back to the Toyo R888R and I don't have much sizing options being 19/20 and I don't plan on selling my wheels b/c I love them. 285 could work but afraid the .8" difference being below 1" could cause issues. I think the 295 would be best but I would prefer the 305 b/c the height difference is only 1.4" Wanting to keep around 1.2" difference because the way the car sits now is really good. I'm not wanting the 275 below because the 275 I have now to me isn't wide enough for the 10" rim and the tire curves at the top even though the height difference is closer at 1.1".

All of these are Toyo R888R with the rear tire being a 325/30/20

275/35/19 would have 1.1" difference
285/35/19 would have .8" difference
295/30/19 would have 1.7" difference
305/30/19 would have 1.4" difference


Attached a pic of my spreadsheet b/c I'm OCD and it may make it easier to see.

Capture.PNG

The key is the relative ratio between front and rear vs. OEM not just front tire height or rear tire height compared to OEM. OEM front is 91% the height of the OEM rear. I believe if you keep to approximately this ratio front to rear then you are probably close enough. Problem comes up, I believe, when the ratio front to rear is substantially different from stock. Unfortunately I don't know how much of a difference the system tolerates. I do know that the 315/30/18 front and 345/30/19 rear Hoosier combo did not work on my TA.

[PkB2014]

The key is the relative ratio between front and rear vs. OEM not just front tire height or rear tire height compared to OEM. OEM front is 91% the height of the OEM rear. I believe if you keep to approximately this ratio front to rear then you are probably close enough. Problem comes up, I believe, when the ratio front to rear is substantially different from stock. Unfortunately I don't know how much of a difference the system tolerates. I do know that the 315/30/18 front and 345/30/19 rear Hoosier combo did not work on my TA.

Yep it's all about the ratio. Keep within 4% of the stock ratio (I think it's closer to 5% maybe) and you should be ok. YMMV

[Next Phase]

For reference, I'm running 18's front / rear with 30 series front and 35 series out back (Hoosier A7) and no issues with stock settings.