235/60s in the front is no problem. 245/60s is the limit, because you start getting into body tolerances, wheel backspacing, ride height, etc. to decide if they fit or not. 255/60s WILL NOT fit in the front. They are just too tall. I tried just to be funny with my Challenger (15x8 rims, 4.5" backspace), and no go. The problem is the top of the tire wants to turn on the fender lip. Height is the problem, not width.
My street tires are 245/45 17s and my race tires are 275/40 17s. I have a very slight rub that only happens at full lock and suspension load (race tires). I'm going to run more negative camber and a much stiffer suspension so it isn't going to be an issue (not like its one now).