I have 12 of the old type disposable flotation tires.10 of them leak.All 10 have dry rot cracks that leak .The cracks are between the treads.I have been reading that many old timers would use evaporated milk in side of bike tubes to stop leaks.The theory was the milk sours gets rancid and changes to a nasty gell that seals leaks.The only drawback was that if the tire ever blew out was the smell was likely to make you vomit!-I am about to try it as I just dont have the funds to purchase new tires and wheels.I wish the cracks were on the sidewalls then I would try an exterior patch.Tractor supply sells a vulcanizing rubber roof repair buy the gallon that states it gells into the rubber .I am thinking of trying that also.Just thought I would post and see if anyone has tried any of these.I did buy 2 cans of rv fix a flat to put in the tires but I fear that it might not work.Any suggestions???