I agree with Woods74, especially if you want to set it up for handling. I got 225/40/17 on a 8" wide up front and I managed to stuff 275/40/17 on a 9" wide in the back.
Did you have to move your springs at all? I'd love to stuff some 275's under my car. Mopowers was able to do it with his car as well. What wheels are those, and do you know your back spacings for front and rear? Oh and what wheels are those? Love 'em.