FJ40 OEM Steelies widened to 8" - Backspacing?

[lelandEOD]

I've got a set of old steelies I'm going to have widened by Stockton Wheel to 8".

I've tried a search but haven't found anything. What backspacing/offset should I specify for my FJ40 to clear the 4Runner disc brakes?

Thanks in advance!!!!!

 

[Fast Eddy]

3-1/2"