i used to run 33x12.50x15's with a 3" BL and i didn't have any rubbing issues at all except for when full locked and flex
i now run 35x12.50x15's with the 3" BL and 6" susp lift and i know i could run 38.5's without any issue, and when i find a decent set of them, i'll let ya know!:smokin: