Swaying with new rear tires.

[Count Mackula]

Yeah, it's always best to check tire pressures after they're mounted. Shops always over inflate them, usually to 40+ PSI and that makes them feel scary on the highway.

I appreciate the feedback! Thank you.

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[AP1]

The problem: I have a 21 3.0 with stock wheels. At 19K miles, I noticed the rear tires wearing out on the inner part of the tires. I decided to replace them (JUST THE REAR TIRES). I plan on replacing all wheels with TE37s with new meats and wider wheels in the near future. So I just replaced the rear tires for the time being with Firestone INDY. Had them mounted and balanced.
So upon driving the car, I took it on the freeway and the fucking car started swaying on me. I remember reading that a bunch of people had the same problem with other tires. Figured they were exaggerating. But the damn car is terrifying it drive while it’s swaying. The traction control would kick on at 80 MPH on turns you would NEVER think it would ON FREEWAYS.

I figured that the car would eventually straighten out and stop after a few hundred miles. But I want to know why. I googled it and read a bunch of threads and etc. Several people have mentioned that it’s lube of some sort that needs to wear off and etc. (which I doubt)

Any idea what it might be? And how did you guys solve this issue? I’ve had several RWD cars and replaced ONLY the rear tires on many of them and never had this issue. What’s the reasoning of this?

As it was mentioned above - alignment work is a must if any uneven wear is observed. Next issue is different type of tires front and rear. This could be OK for a truck, but NOT for performance car. It is also known that overinflating tires causes problems in turns. Always keep pressure closer to bottom of recommended range. This is even more important at hot climates like eastern CA.

 

[Heavy Foot]

Oh damn… did you get it fixed? So these clowns that changed the tires inflated it to +40 PSI and I dropped it down to low-mid 30s and it didn’t sway anywhere near as bad. Were your tires overinflated as well?

No, the tire shop inflated to the correct spec. I'm booked in for an alignment in a few weeks after my new MSS sleeve kit settles.

 

[razorlab]

Stock tires aren’t dunlops

 

[romanLegion9574]

alignment, check your pressures, and different tread types are all potential causes. I had the same issue when I got my rear continental A/Ses delivered a couple of weeks earlier than the front.

 

[Last Lemming]

Btw any amount of sway is NOT normal, just dangerous

 

[TheBayA90]

You might want to check the speed ratings on those Firestone Indy’s. I’m almost certain it doesn’t match your front PSS.

 

[underdonk]

"Sway" is an interesting choice of words here. I can't say I've ever experienced a feeling like that on any vehicle I've owned, regardless of type or tire. Are you feeling them track the imperfections in the pavement?

 

[NitroYellowMKV]

I have this exact same issue, when I went with PSS 305's. ruined the car. I finally went back to 295 conti extreme contact and it seemed have to fix the sway in the rear but just in time for my steering rack to fail and the car being undrivable in the front lol... There is a big issue with tires on this car, super picky and annoying. I was also experiencing traction control going on like crazy and no stability in the rear.

 

[Loco38SUP]

I have this exact same issue, when I went with PSS 305's. ruined the car. I finally went back to 295 conti extreme contact and it seemed have to fix the sway in the rear but just in time for my steering rack to fail and the car being undrivable in the front lol... There is a big issue with tires on this car, super picky and annoying. I was also experiencing traction control going on like crazy and no stability in the rear.

I’ve always preached that the 265/35 front and 295/35 rear 19’s are the best all around setup on stock suspension. The car feels super stable with these sizes.

Anything bigger and you need the SPL goodies to get angles back to a good place.

-RJM

 

[OneTimeAccount]

I have this exact same issue, when I went with PSS 305's. ruined the car. I finally went back to 295 conti extreme contact and it seemed have to fix the sway in the rear but just in time for my steering rack to fail and the car being undrivable in the front lol... There is a big issue with tires on this car, super picky and annoying. I was also experiencing traction control going on like crazy and no stability in the rear.

Wait, when did your steering rack fail? Before or after your track day with it? What failed on it?

 

[65sohc]

I installed Toyo R888R: 305/35's on my stock rear wheels to improve traction after tune. Never had any instability when mated to stock front Michelins.

 

[NitroYellowMKV]

Wait, when did your steering rack fail? Before or after your track day with it? What failed on it?

from what we can tell it is has been failing for a while, I think the track day just pushed it over the edge

 

[SpeedRacer]

from what we can tell it is has been failing for a while, I think the track day just pushed it over the edge

The electric power steering rack on my 2021 went out when my car had 1,500 miles and the dealer had to replace the whole assembly.

It’s bone stock and has never been tracked. All I was doing the day it failed was picking up steaks for the grill and I doubt that put any stress on it!

I guess my point is the Supra sometimes has issues with the electric power steering rack failing (similar to the Z4). It seems kind of random.

 

[A90.C]

I had the same thing happen when I replaced just the rear tires as well, only on freeway above 70 or so. Went to 285 on stock wheels. I chalked it up to new tires breaking in, eventually stopped after a few weeks of driving.

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