be able to...
If you stick with 10" wheels, it should be as simple as less backspacing, but you need to figure out how much.
With 8" wheels, it needs less backspacing also, but not the same amount.
Figure you take an 8" wheel and a 10" wheel, with the same backspacing. Put a 12.50" wide tire on each. The tire is going to center over the wheel. So the tire center of the tire will be 1" further out with the 10" wheel, meaning the inner edge of the tread should be 1" further away from the radius arms. Make sense?
So to keep the inside edge of the tire tread at the same spot while switching to an 8" wheel, you would need 1" less backspacing.
I think that makes sense....
I don't know I didn't sleep much and headed to work, but I think I got that right.