Swing-out Biggest tire

How much weight can the stock rear bumper brackets hold. I scored a bumper/receiver/swing-out at the bone yard, but I had to cut the receiver brackets off of it to get it out. The last owner had welded the receiver to the bumper and all the mounting bolts were welded to the receiver as well. So can I put a 31" tire on a bumper with the stock bumper bracketes and no other supports? Seems like 8 bolts should hold it on pretty good, but once I hit the trail it may be a different story. What say you?

The max. rec. tire size for a stock tire carrier is a 31