Ordered BFT MTs 35x12.50 Tire options I found

[4alarm]

to be quite honest the backspace really doesnt have anything to do with the calipers rubbing since the backspace is the distance measured from the wheel mounting surface to the inside rim (assuming something flat was put across it to get the measurment) so that being said no matter what the backspace is the face of the wheel never moves what causes rubbing is actually the design of the wheel and curve of the face....

Unless the inner rim is rubbing the top of the caliper. I fit 15" wheels on 3/4 and 1 ton chevy axles (requires 16" wheel)but had to grind the top and a little of the sides off the caliper to keep it from rubbing.

Maybe the wheels have a bit of a back bend to them past the WMS?

 

[CruisinFJ60]

well obviously if the inner rim is rubbing a larger wheel is required. or modifications to make a smaller wheel fit where a larger one was originally required.
but yes again some wheel will have more of a curve than other after the WMS which is why some rub and some dont.