Random question for a 1968 firebird.

[c4racer2]

well - they probably list what the MFG publish. But it's reasonably good data in my experience. For example I just picked up a set of 275/295 Nitto NT05 and the published specs were absolutely spot on. But it's also very true that not all 275-35-18 tires are the same (or any size, just using that example). The Nitto's for example tend to run on the smaller side of things for most sizes, but the 295 is right on par with other mfg's tire.



Best thing is to do as much measuring as you can because I don't think there is ever a one size fits all scenario when it comes to wheels and tires and a customized pro-touring car.