I stretch the 1/4 panel wheel opening five inches on my 1971 street Duster so I could run most any size street tire I wanted to. I have a set of steel aftermarket wheel tubs that go up flush to the stock rear sub frames with ladder bars and coil overs, this picture is with a set of MT ET Street radials, 315x60x15 on a set of 12 inch wide wheels with 6 3/8 back spacing. The rear end is one inch narrower than a stock A body 8 3/4 rear end also. I wanted the cars apperance to look stock so the street racers wouldn't to get alarmed