http://www.4wheelparts.com/Wheels/Mi...pn=M%2fT479412
4.5" Back space will rub with 33x12.5s... I had that with my 2.5" leveler on my 4wd... so you'd for sure rub.
these wouldn't rub AS bad..
http://www.4wheelparts.com/Wheels/Pr...n=PXA1079-7938
but I think they'd still rub... wide tires alone are a problem... then to get wide rims on a titan, seems to need a somewhat negative offset to clear the tires from the suspension/frame... so it's a fine line... I don't know what is the most and least backsets that clear the inside because I didn't rub there, I know what rubs on the fender/pinchweld a little... tires that stick out at all
so for my best guess.. I'd have to say probably a 10" wide rim w/0mm offset or VERY slight positive offset would clear the best. but this is a guess as I never checked the inner clearances... and basically, it's one or the other, and it'll still have problems