So we're talking about 2 things here. (1)Aspect ratio, which affects overall diameter and the (2)width on a 9.5" rim. The 275/45/20 setup is close (29.7" vs. 30") to the overall diameter of the dealer recommendation, I say go with that as long as it doesn't rub. I would agree that the 275 is a better fit for the 9.5 width, 255 is not enough IMO.tjh2dUVA said: