I don't see anybody who makes a 275/45-17. Most I can find is 275/40-17. They will fit '05+ Stangs. They are about 1" shorther than OEM. That will require a retune for the new revs per mile. It is quite possible that the '94-'98 wheels having less backspacing than the '05+ will stick out further than S197 wheels.
they do stick out. many people say they dont, but if you look at them closely, they do. its not much, and some like the look. i prefer to stick to the proper offset.
I bought 275/40/17 drag radials for race days and mounted them on Saleen 17x9 replicas that were supposed to be the correct offset for S197's, but once mounted, they stuck out a little anyway. They are shorter, so I have to recalibrate my speedometer for track days, too...