[grill-n-go]

I just went out and looked at my TM...

It appears that the tire support sits on top of an angle iron thats welded to the frame. See if the attached picture helps. The pins are designed to keep the support bar from popping up, they don't carry the weight of the tire.

I've never taken our spare off, and from time to time I miss the mark by a mile, but the aforementioned is my take on it.