the best thing one can do for a tire is keep it in an upright place in a dark and cool enviornment, as for on a vehicle long term storage they should be hanging in the air, as for a tire cover that is the single most bestest thing a person can do, direct sunlight is the absolute worst culprit for the damage to ones tires, UV light brakes them and all things down first then basic weather conditons ...to dry to wet u name it degrades from there, but it is UV light that is the worst and the starter of the damage, this site has the best stuff I have seen or read about to keep em on the road as long as possible... greatlakescorrosion.com I use the tent halfs and all my tent covers holder thingys to cover my tires on the 2 5 tons and the deuce and the M38 and even the Mule and treailers when they are not in there sheds, even for a few days I cover em all before I leave the shop, just to much of an investment not to... good luck, keep em clean and at least a quality wheel spray and cover em.....