rjwz28

I just did a little bit of footwork on the original Michelin Pilot Sport, and even though it is no longer available in the 345/35-18 size, Michelin recommends the 345/30-19 that they still sell be mounted on a rim from 12-13.5" wide. They measured section width on a 12" wheel as they have with every more recent 345 tire in their lineup, but the fact that the range of recommended wheel sizes is pushed up .5" on the bottom end and a full inch on the top end indicates that this tire either is wider or has a higher sidewall/tread stiffness (or both) such that it does not work well on the smaller wheels (as you observed with yours). Every other 345/35-18 and 345/30-19 I've seen available on the market, both from Michelin and others, recommends 11.5-12.5", with the Hoosier A6, R6, and Kumho 710 track/autocross tires in those sizes recommending 11-13" wide.

It's interesting how much variance there is in tires sold as the same size.

mrr23

Manufacturers decide what percent ratio of section width to tread width they want to use. It ranges from 80 to 98 percent.

This why one tire looks wider than another of the same section width. That first number of the tire size is the measurement from sidewall to sidewall.

mrr23

An update. With the car lowered, they did rub the inner fender. So I raised the car up, went with 325 / 30-19 tires, added a 5/16 spacer and realigned it.

mrr23

Another update. Raised the car up another 1/2" because tires would hit on a large bump. Took the spacers off and no rubbing of inner fenderwell. Car is back to stock height.

mrr23

picture through the side mirror

mrr23

To take care of the slight rub on the inside I put these on. They were from my old 3rd gen fbody trans am. Factory gm 1/8" thick steel spacers. We're put on the rear with drum brakes to help clear the wheels.

RomanNYC

which Michelin did you choose?

mrr23

i am currently running cooper zeon 325/30-19 in the rear.