Max back spacing
 

I have a 74 1303 any I'm trying to fit tires for it with a 10 x 15 inch rim on drums in the rear. The back spacing on the rim is 4 inches - I'm trying to see if a 295/50(11.6 width) will clear on the inside or if a 275/50 (10.8 width) would be better - I have to order the tires from online so I can't do a test fit