what offset do you have and are you lowered? I've seen 255 before too though. but thats a lot of meat up front for the everyday person.

i wouldnt go above 235 unless you really nead more bite for something. above posts are also important to notice the idea of width of rim. 225 on a 8inch wide is no stretch and no balloon look. 205/215 would be better look and perhaps better handling (less sidewall balloon flex) on turn-in. try using better compound tires (higher performance) before getting too big/ballooning the tire sidewalls.