i want to sell my 20 inch torque thrust wheels and switch to chrome hot rod steel wheels in 15" i have seen that i have to shave thr caliper , but does anyone know what offset or backspace i need to run? i am looking at hrh steel wheels with some wide white walls to match my 52 fleetline (i know kinda cheesy ) any info would help, and the truck is slammed 6frt 8rear