The difference in center offset between my original 15 x 6.50 BBP Rallye wheels and my original 14 x 5.50 SBP Rallye wheels is 1/8 inch so the 8 1/4 rear should theoretically be 1/4 longer drum to drum to keep the wheel in the same position in the wheel wells. Just my logic, I don't have an 8 1/4 rear to measure.