I currently have 33x13.50 LTB's on a 15x8 wheel. They will work no problem.
I ran 33x12.50's on a 15x8 on my 93 4 runner had no issues loosing a bead or anything I ran them at 12-14 psi offroad..
There's a guy on pirate running 38x14.50 TSL/SX's on a 15x8 wheel.
I think his name is TNToy on there.
here's a link to his page:
http://home.off-road.com/~mithrandir/38.5/