I really don't understand the obsession with cramming as much wheel and tire under there as possible...sure, there are practical considerations...more tire is more grip, and larger wheels clear larger caliper/rotor combinations....but in the end, even for those of us building for handling these are not race cars...there are very few vintage mustangs out there that can make use of 18" wheels with 245/40/18 tires. I mean, I appreciate a larger wheel than stock and am myself using 16" wheels with a 215/55/16 tire....but you wont ever see me run anything larger than a 17"(even a 17 verges on cartoonish looking in a 66)...and I would only ever consider a 17 because of the larger rotor I would be able to run....on a stock car with stock drums though? 15 or 16 at the most.