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Originally Posted by GT speeder13  Ive been looking into buying some GT500 replica wheels, but I am really confused as to what tire sizes I can fit on these rims. The rims measure 18x9.5", and AM is recommending 255/45-18 for the tires. I was figuring that with 9.5" rims I would have to use a 275 or higher. |
Shelby GT500 comes with 18x9.5" rims with 255/45/zr18 front tires and 285/40/zr18 rear tires. These metric sizes translates to 10" wide tread fronts and 11.25"wide tread rears. Both of these tread widths can be accomodated by the 9.5"wide rims. The fronts are 45-series tires (sidewall height equal to 45% of the front tread width) and the rear tires are 40-series (sidewall height equal to 40% of the rear tread width) in order to keep the tire height (overall tire diameter) of the fronts and rears approximately the same (best for suspension geometry). The wider rear tires still fit inside the wheelwells, but the front tires need to be narrower to avoid rubbing when turning.
Guys going up in wheel diameters need even lower series sidewalls in order to remain close to factory tire height. Which is why you see 35-series front tires and 30-series rear tires used with 20" diameter rims.
Car and Driver magazine did a sports car tire comparison a little while back. The Goodyear Eagle F1 supercar tires performed the best and received a score of 1050 out of a possible 1100 points. Goodyear F1 tires are factory equipment on the Shelby GT500 and the 'vette Z06. As I remember, Conti-sport tires placed second (well behind the F1s) and Yokohama third. I believe BF Goodrich TAs placed tenth at just under 1000 points (still a very good score).
GT500 wheels, what are the tire specs? 
. Excellent.
