Tires cupping
 

I've noticed my rear tires have been cupping on the inside for quite some time now. I've since rotated my tires (8000 miles ago) and several months later went to Evasive for a realignment & corner. Since the alignment, i've placed about 5000 miles on the car. Never once did I notice the tires bouncing indicating a bad shock or poor bushings. Can someone shed some light on why this may be happening? One thing to note is that my corner balance was off prior to going to evasive (maybe ~20%); but doubt this was root cause.

I'm due for new tires soon (now) and need to take any precautions before ruining another set. When the car is lifted, the wheels do not have any bearing or suspension play whatsoever.

My setup:
255/40/17, 17x9 +44 Star Spec. 38 psi HOT
Kaaz 1.5 LSD
Tein SRC. Front/rear compression & rebound ~ 8 clicks out
Gendron 1-5/16" FSB on full stiff
Js S1 Camber Joint
AP2 rear swaybar (25.4mm)

Alignment:
Camber: -3.3° all around
Front Caster: 8.1
Front Toe: 0
Rear Toe: +0.25" Total

Here are the tires as it stands today. The cupped rear tires are now on the front since the rotation, which has been about 8000 miles. They still haven't worn down to normal.


http://img529.imageshack.us/img529/6554/82202084.jpg http://img26.imageshack.us/img26/7039/57222115.jpg

http://img690.imageshack.us/img690/7027/53121452.jpghttp://img72.imageshack.us/img72/4492/73895754.jpg

wow so its cupping on all 4 corners?

wheels balanced properly?

I don't get any wheel vibration, so I'm assuming they're still balanced properly. It does almost seem like all 4 corners are cupping to a certain extent.

Just another data point - my original S02s did something just like that at about the same mileage. I had them flipped to get more wear and ended up with a huge vibration over 70. Even balancing on a machine that applies force to the tread helped almost not at all.

I checked the alignment after replacing the tires and found it all over the place. Since the car was new and I picked it up at the beginning of winter, I hadn't checked the alignment from the factory. After the alignment, I never had the problem again on any tire. Not sure how a wacky alignment would cause it but...

Good point. With my recent alignment I hope whatever problem was there is now gone. I read somewhere, once a tire cups it will continue to follow that wear pattern forever. I believe that's what going on here. I'm gonna go recheck my alignment using the string method to get a quick readout.

BTW, this is the only set of tires I've cupped. My previous sets had no issues whatsoever.

http://www.procarcare.com/includes/content...adtirewear.html

Rear toe-out might be the problem. Most guys will run slight toe-in for the rear.

Agree. Never experienced this in the S2000, but other cars set-up for the track, absolutely.