I'm trying to find out what the largest tire size is that will fit on a stock 2001 F-150 Supercrew 4x4. I saw an extended cab F-150 the other day that had 315/70 17 BFG All Terrain T/A K/O on factory rims, and was not lifted. I waited around for a while to try and talk to the owner, but never got to. I got down and looked under the truck and at the tires and they did not appear to rub anywhere. The only thing I saw was a small piece of the plastic air dam cut out on the very bottom of the bumper. does anyone else have a tire this large on an un-lifted truck with factory rims ?