Best guess assuming that you're looking at both sizes in the same tire mfr's model - the 285's will ride a tiny bit better, the 275's will give steering that's just a little more responsive and precise. There's about a 1% difference in diameter and revs/mile, which is meaningless for all but the fussiest needs/wants.


Norm

 

Now this is a thread one can dig into and learn. Thanks Norm, now I feel ok about 9" w/275's vs 10" wheels with only a 285/40 18. I just fitted 255/45/18's due to a hurricane as an emergency choice on the rear. Bridgestone pole positions.Then bought 255/40/18 Firestone Indy 500's for the front. Once I wear these out I should have the coin for wheels.