Larry, I"m planning on installing either 17" x 9" wheels front and rear or 18"x 9.5" wheels front and rear on my 71 GS. What back spacing will be required for each wheel size? Thank you for your input.
Ken, I know 4 1/2" works on an 8" wheel in the front. Theoretically, a 9" wheel will want another 1/2", so I would say 5". Not sure though. I would measure. Maybe someone who has done this can advise you better. In the rear, the 10" requires 5 1/2"- 5 5/8" of back spacing. I would think a 9 1/2" wheel will want nearly the same.