Checked online and read both sides so nobody knows. On rims on their side, off rims standing up. Some say air pressure higher than the tire is suppose to have, some say only 15lbs, ?????? Please help me Scotty.
It's more important to keep the tires away from, heat, UV light and ozone (generated by many electric motors) - these degrade rubber.
I usually store for 2 different reasons...1) Bought aftermarket wheels and tires and store the originals for to put back on when trading in. 2) Keeping stock wheel but changing tires to something better or more practical; so then it's only the tires that get stored. Either way I get the big plastic bags they give you from Discount Tire and wrap each individually and stack them on the side and put in a cool dark place.
Remove the tires and store them in a storage on their sides.
I always see them on their sides stacked up, maybe for good reason?