Tractor Repair: Ford tractor model 1910, ford tractor, left front tire

Question
My left front tire would not turn when it got very cold and I put some heat from my exhaust to the outside of the hub and it broke loose, what would cause that tire only not to turn and freeze up like that?  It is a 4 wheel drive 33h.p. tractor. Someone suggested water got in there and another said maybe the bearing.  What do you think?  Thanks for taking your time to help.

Answer
Well I would first suggest to drain out the oil and see what you find. If there is no metal then water could be the problem. It would have to be a lot to freeze though and be evident in the drained oil. Install new oil and see if it happens again. If it does then it will be time to take it apart and see what is the cause.