I work at tire pros, and we have a set of bolt extractors just for this problem. Just hammer it on snug, then hit it with a breakrer bar or impact. 12pt socket will do the same if your willing to sacrifice it, but you would have to really hit it on there good before trying to turn, otherwise it'll slip. A big set of vise grips sometimes will work too. I would never weld on it because of the heat damage. I think big mike took care of that though...
