I know a fellow who is running 31x10.50 BFG MTs on the stock rims. The only problem he has had is with a bit of rubbing on the front springs and maybe a little on the inside rear wheel well. That would be at full lock in the front and full flex in the rear. I don't think you would have a problem at all. 15x7s would be ideal, but if you don't have the coin.........
DON'T FLIP THE RIMS!!!!!! That is very dangerious if you are driving street or hwy. They will fit but you can also go to a auto salavage yard and get wider stock Ford half ton rims for next to nothing. Just don't flip the damn rims.
Manitoba Trail Masters
86 Samauri,4:57s,Lockrights at both ends,Hedman header.31s,spring over,high flex leafs.10,000lb home made hyd winch and long travel shocks