You might have to use a 1/8" or 1/4" shim to space the tire away from the frame. This depends on the alignment of the body on the frame, and if you have had any damage to the frame. Also, check to make sure your rear control arm bushings are in good shape.
I have run 275's without shims on my car, but it is too tight if I push in the corners.
You should have a lot of clearance on the outside. I have my rear dropped 1.5" and have run 275x60x15 with 8.5 inch rims (BS of 3.75") and not had a problem.
Deep Enough
Donald McMullin
