In street driving, I think you would be hardpressed to notice a performance difference between a 265 and a 285. In fact, a 285 would cause MORE understeering feel in the cars handling. In fact, if the newer tire is "stickier" than the older tire, a 265 might give identical performance feedback. Some say, size doesn't matter
Not all tires are created equally. I've seen some "205"s that were as wide as some 225's. Each manufacturer makes tires differently. Just like shoes.. you may wear a 10 in one brand and an 11 in another or a 9.5 in another. Same with tire sizing.