I have the Rancho 3" kit, with 315/75R16s on 16x8 wheels. Very minor rub on the rear of the front-driver inner fender lining (that make sense?)
Anyway, 35x12.50R15s on 15x8s would rub like mad, I expect, but the different offsets of the 15 and 16" wheels should allow you to run most 35x12.50s without rubbing. Just look at the "real" size, not the advertised size.
i.e. Jason't 35" SSRs need a 3" body lift to clear as they are 35.5" tall and something like 13" wide.
But 315/75R16 MTRs and BigO XTs and BFG MTs are all 34.5-34.8" tall, and 12.50 wide, and fit fine, and look great!