Check out nitto terra grappler. They have a 275/55 (31.8" close to stock)and a 275/65 (32.99" inch taller than stock) that both fit on the 7.5in rim. However I dont know if the later will fit without a lift.
I recommend that you ditch the 20" wheels. Trade for someone with 17" wheels, then get offroad tires for those wheels. You want more sidewall offroad than you get with 20" wheels.
I would think 33 x 11.5 's will take some pretty major inner fender trimming. I'm running 275/70/17's BFG's which are 32.2 x 10.8's with a 2 inch lift and 1.25 inch Spidertrax spacers and I'm still getting some minor rubbing when backing up and the wheels cut the whole way. It's rubbing on that rib in the front fender well.
I recommend that you ditch the 20" wheels. Trade for someone with 17" wheels, then get offroad tires for those wheels. You want more sidewall offroad than you get with 20" wheels.
i totally agree with going to smaller than 20s, but if he wants to use em with a "wider" offroad tire,(not sure what his idea of "wider" is) i assume he has a lift or intends to install one & do alot of trimming, he may also never intend to go offroad, he also didnt state what height tire he was looking for, (stock height,31s,32s, 33,35,) but if he wants wider than 11.5,( i dont understand why) he most likely have to go with an increase in tire height also. harper7, did you try moving the inner fender forward? if not, thats an esay way to solve the problem without cutting,(trimmed tip of bumper also) i had to do it with my 265/70/17 & new wheels, it can be moved at least 2 in. forward, just am idea.