wheel and tire size with grater

[BiG_MaN]

I have an 94' S-10 and I want to run 18" front and 20" rear wheels with a RaodGrater/ Coolride system. My question are:

1. What width rims to use
2. What is the proper backspaceing
3. What tire sizes to minimize rubbing

[darren@ridetech.com]

Not sure about the backspacing, but up front we used a 235/40/18 with no problems. In the rear you need at least a 27.5" tall tire and you can go as big as 29" . If you tell the wheel manufacturer what you are doing they should be able to tell you the back spacing.