I had a flat tire on my dolly , looked and tire is just dry rotted and split. First thought get a new tire for plugging the split out of the question. In my car trailer I had put a tool that needed to be put somewhere else but seeing it came an idea. It is a tool you place cans of foam in to shoot inside cracks of walls in homes. I build houses and thats what I use to fill with. You can buy the cans at lowes and use without the gun , Anyway I stuck the nossile into the split of tire and shot that sucker full of foam. Forgot about it till later and as I went by I stepped on tire and it was hard as a brick, so I investigated closer. Dag solved my flat tire problem forever on that dolly. My lawn mower leaks down at times, gona make a hole and fill those suckers up as well. Got a flat small tire? You fill it up like that , no more worrys.