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I cross posted the following in a autox/road racing section of a corvette forum. I know we only have a few other corvette drivers in the club but I was hoping some of you may be able to chime in....

I have been experiencing some weird tire wear on my rear tires on both my street and autox tires. I have a 99 Coupe. Street tires are run flat Michelin's and autox tires are Falken FK451's. Both are standard size. (275/40R18)

Conventional wisdom tells me I have them overinflated. However on my street tires I have always had them at the recommended pressure with the exception of 2 times autoxing on them before I got the other wheels/tires for autox. Intially on the Autox tires (Falkens) I ran close to 38psi cold in the rears fearing rollover. As the autox season has progressed I have be taking them down to the point finally this past weekend I got to where if they were any lower I got rollover. This was about 31psi cold. I ran all weekend at that pressure. Prior to the event I had about half tread left in the middle. My car was co-driven this weekend and I had a few runs playing around during setup on Friday. In total probably about 20 runs on a real abrasive surface. The middle of the tire is now nearly corded and there is probably an 1/8th inch or more tread a 1/4 of the way in on the tire on either side. The edges are probably about 60% used up.

The tire profile looks something like this ---\___/---. Its not as drastic as that figure but hopefully you guys get the idea. I will try and get some pictures up at some point.

I have not had any kind of aggressive alignment done as I drive the car daily. The alignment should be in factory spec unless it has been knocked out of whack. Having said that I still don't see how alignment could create that kind of wear issue. The only logical thing I can think of is over-inflation. But that doesn't make since either since I ran them as low as I could this weekend without them rolling over.

Also like I stated above this wear pattern is occuring on my street rear tires as well although not quite as excessive. And I don't horse around on the street tires. This is exclusive to the rears only. The fronts seem to be wearing normally.

Can anyone offer some insight as to what my problem may be? Is this just typical of Corvette tire wear?

TIA

Chris

Chris,

In my experience with a range of cars from gutless wonders with open diffs to torquey V-8's (Mustangs) with limited slips the center portion of rear tires always wears faster than the outside edge. Inside edge wear is very dependent on the car (solid axle vs. irs, alignment, etc.). Note that with a decent limited slip like your Vette presumably has there will be "dragging" wear on the inside rear tire when you make turns, especially when making 90 deg turns, even when being very gentle with the gas. The only solutions I've found are 1) rotate tires front to rear frequently to even out the wear. 2) Corner harder so that the outsides of the rear tires wear more. Lower rear pressure doesn't really solve the problem for me. Of course, for the autocross tires you will get wheelspin which causes more center of the tread wear.

Dick

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Dick Rasmussen

FS 50 2018 Mustang GT