I had a set of Goodyear GT+4'* installed on my car before (just moved to a normal size aquasteel for the winter, new 18'* come spring). The ones I had were 255 50R16'*. They fit, but at full lock in the front they would rub the plastic inner gaurd between the frame and the tire. In the rear the welded lip had to be pounded back (lip between the bottom of the trunk and the inner fender wall) to avoid sliceing the tire on suspension compresion.
The grip and cornering I recieved from the wider tire was amazing. I hope to get a comperable width tire when I get my 18'*.