245/60's will fit on 6" wheels, but it's pretty much the limit. are you sure you're wheels aren't 15x7?
I think the 15x6 wheels came on the big car only, with 5 on 5 bolt pattern. 245 is actually a size or 2 over what the mfgrs recommend, but it sounds like many run them w/o issues. Might depend on your driving habits.
