I am building a full fendered Model A car. the nine inch has been narrowed to 55 inches. I want to run 8 inch wide rims on the back. Does 3 1/2 inches sound right for the back spacing. I really want the tires to fit under the fenders, not stick out. It's a roadster, could I run 9 inch rims with 4 1/2 inch back spacing?