[NeXvZEiN]

I put on a new set of rims about seven weeks ago, give or take, that were upsized all around to 1LE sizes. I had planned on getting the Nitto 555 tire, but the shop I went to convinced me to get the Firestone Firehawk Indy 500 tires. They ended up putting on 275/35/20 up front and 305/35/20 in the rear, no 30 series available. I had zero issues with the set up until last week.

Around Wednesday of last week, I noticed that when I ran the engine up to around 3500-4000rpm the traction control light would start blinking a lot. It did the same when braking moderately hard. This only happened when the car was cold. Then this weekend I decided to open it up on a freeway on ramp. I got it up to just under 6500rpm and I was expecting the car to switch to performance shift. Instead the car cut power, like bouncing off redline but more severe, and the traction control light once again started to go crazy. Expecting the car to be in limp mode I slowed down, but the car was back to normal after that episode.

The dealership is blaming it on the tire size in the rear, but that doesn't make sense since it just started happening. One shop thought I may have hit a wiring harness in the rear wheel well. Bottom line is no one has a good answer for this and I'm completely stumped.

Any help or guidance would be greatly appreciated. TIA

[arpad_m]

305/35 rear tires will definitely rub against the wheel well liner and indirectly the driver side body wire harness, see this thread for a solution: https://www.camaro6.com/forums/showthread.php?t=485975

If that is indeed the problem, let's hope your wire harness hasn't completely rubbed through beyond repair, I've heard its replacement is very labor intensive...

[Gunkk]

If your front and rear tires have too big a difference in overall diameter, the rotation rates will be too different and confuse the stabilitrack and cause these kinds of issues.

Solution is to replace the tires with the correct sizes.

[arpad_m]

Originally Posted by Gunkk

If your front and rear tires have too big a difference in overall diameter, the rotation rates will be too different and confuse the stabilitrack and cause these kinds of issues.

Solution is to replace the tires with the correct sizes.

Yeah, this is true as well, thanks Gunkk It must be hovering on the verge of the tolerance range (the total absolute diff is 3.3%) and that may be why it only triggers the issue occasionally.

Notwithstanding that, I'd definitely look into the rubbing as well, it's very likely to occur with this tire size.

[srcstc]

There's so many threads on people using 35 over 30. Why does everyone insist on deviating from the tire size that's known to fit for a taller tire?


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[KingLT1]

If you didn't relocate the harness then you might of damaged it. 305/35/20 will rub through the liner on the driver side if the harness isn't relocated.

That being said in general 275/35/20 is 27.6" tall and 305/35/20 is 28.4" tall. That is within 1" and should work fine without causing TCS/Stabilitrak to freak out. However some tires are taller or shorter then advertised. I have been running Nitto G2 245/40/20 and Nitto R2 305/35/20 with the harness relocated and I have no TCS/Stab issues.

[NeXvZEiN]

I haven't had any rubbing issues at all. The harness is the only thing I can think may be an issue since the tires have been on for so long and the problem has only been around a week. Would the issues I have be symptomatic of the harness being rubbed?

[ctrlz]

Originally Posted by arpad_m

It must be hovering on the verge of the tolerance range (the total absolute diff is 3.3%) and that may be why it only triggers the issue occasionally.

I think this is what is going on.
My math shows a diameter difference of 2.99% between front and rear with this setup. I am guessing the sporadic nature of the flashing indicator has to do with tire pressure and different warming rates for the front and rear depending on the situation.

I would switch the info display to tire pressure. I would slightly overinflate the front tires and slightly underinflate the rear tires and see what happens.

[NeXvZEiN]

Originally Posted by ctrlz

I think this is what is going on.
My math shows a diameter difference of 2.99% between front and rear with this setup. I am guessing the sporadic nature of the flashing indicator has to do with tire pressure and different warming rates for the front and rear depending on the situation.

I would switch the info display to tire pressure. I would slightly overinflate the front tires and slightly underinflate the rear tires and see what happens.

I'll give it a shot thanks!

How would I go about locating the wiring harness should that be the issue?

[dmcmahan60]

See the link ARPAD posted