[NateMaro]

Hello all! Hope all is well & Someone can answer this!

So recently I upgraded rims and tires, yes I know the tires size difference is causing my traction control to trigger even though it’s not spinning, also my speed is actually 2mph faster than what’s showing (according to gps) however.

My question is
I currently run Front: 20x9 275x35ZR20 & Rear 20x10 305x35xZR20
My rear tires are new so I’d like to keep them. What would I have to change my front tire size to for this problem to be fixed?

Thanks.

Ps: I saw all the other forums on this but I couldn’t figure the tire size I would need to go to, my gues 275x40ZR20?

[arpad_m]

Hi Nate and

Originally Posted by NateMaro

Hello all! Hope all is well & Someone can answer this!

So recently I upgraded rims and tires, yes I know the tires size difference is causing my traction control to trigger even though it’s not spinning, also my speed is actually 2mph faster than what’s showing (according to gps) however.

My question is
I currently run Front: 20x9 275x35ZR20 & Rear 20x10 305x35xZR20
My rear tires are new so I’d like to keep them. What would I have to change my front tire size to for this problem to be fixed?

Thanks.

Ps: I saw all the other forums on this but I couldn’t figure the tire size I would need to go to, my gues 275x30ZR20?

That 35 aspect ratio in the rear is your likely problem, see https://www.camaro6.com/forums/showt...8#post10957468 for a bit of advice. 305x30x20 or 315x30x20 would work just fine.

[NateMaro]

Originally Posted by arpad_m

Hi Nate and



That 35 aspect ratio in the rear is your likely problem, see https://www.camaro6.com/forums/showt...8#post10957468 for a bit of advice. 305x30x20 or 315x30x20 would work just fine.

I appreciate the help! So their is no size for the front I can go to make it work properly? Once again I appreciate it! Worse come worse I’ll get new rears.

[grampa_ss]

Your mph is off because the rear tire is taller than stock. It’s covering more ground per revolution. Also, you might need to relocate the wiring harness on the rear drivers side. I know all of us with the SS and stock 9” wheels needed to when running the 305/35/20. It’s possible you’ve already worn through the wheel well and into the wiring harness causing the T/C issue

[Mark114]

You have two separate issues. The first issue is that the difference in tire diameter between your current front and rear tires is almost 1". That is likely causing the traction control problem. Switching the front tire to a 275/40R20 might resolve this issue but could cause rubbing issues depending on your wheel offset.

As several others have pointed out the taller rear tire is changing your speedometer reading. A shorter rear tire would resolve this problem and probably resolve the traction control issue at the same time. Definitely check the rear wheel liner as suggested to see if you have damaged the wiring harness. There are numerous threads showing how to relocate the wiring harness to avoid rubbing.

I'm running 20x9 255x40R20 front and 20x10 295x35xR20 rear. I like the slightly taller tires and I'm willing to live with the slight speedometer error in exchange for the slightly reduced wheel gap. I don't know if I needed to move the wiring harness with the new tires but I did it just to be safe.

[grampa_ss]

According to others here, the T/C issue would only happen if the front tires were taller than the rears. The reason is because your wheel speed sensors sense your rear tires moving faster than your fronts. So, you really shouldn’t be having any T/C issues. I run the 245/40/20 front and the 305/35/20 rear, so my front is .7 shorter than my rears. No issues at all.

[arpad_m]

Originally Posted by NateMaro

I appreciate the help! So their is no size for the front I can go to make it work properly? Once again I appreciate it! Worse come worse I’ll get new rears.

Well, it's an equation with many variables that you can change. You need to consider at least these factors: 1) wheel well space, 2) front strut clearance, 3) individual tire heights and, the one others didn't realize or emphasize, 4) the overall height difference between front and rear.

I read somewhere that the TC and ABS systems will tolerate up to ~3% overall (front+rear) deviation from stock, anything more and you may have issues. Sorry, I can't recall the source, but it does seem to apply in your case, as you've introduced a 3.3% overall bias (-0.4% front and +2.9% rear) vs the OEM setup.

So, you can certainly try to bump up the front size to make the overall diff smaller, but then you can easily run into a strut clearance issue. I have only tested 245/40, 255/40, 275/35 and 285/35 in the front, and the last one was a really, really tight fit, I had added spacers to make sure the tire doesn't rub off the rubber grommets at the strut perch.

In your case, even if you don't care about the esthetics of the speedo being almost 3% off, you'd still need something taller up front (at the very least 255/40, but then you might want to go a bit wider for better cornering grip), plus you may rub the wheel well liner with those tall rears, hence my suggestion of just changing the rears and sleeping well afterwards. At the end of the day, it's your call and your $$$

[NateMaro]

Okay! I appreciate all the help. I definitely understand more now and I’m going to see which route I’m gonna take. I have relocated the harness before I got these tire to be safe! Also for some reason my back up cam has gone completely out and will randomly come back on, hopefully that’s not on the same harness as the t/c.