I'm trying to determine the largest backspacing I can use on a '94 4Runner with 1 1/2" bj spacers installed using 16" wheels. I'm going to upgrade to 275/75 or 285/75 tires. I've read alot of threads, and know I can use 4" backspacing, but it would open up my wheel choices if 4.25" or 4.50" backspacing would work. I know wheel backspacing has been covered alot, but I would like to hear from any member that has made a similiar upgrade.