| You are correct in assuming storing them vertically (standing up) will result in flat spots. Store them stacked, wrapped individually in plastic (a garbage bag works well), and if you can, stack them on a pallet or something similar to keep them off concrete in case they slide around (get bumped into).
I have a set of wheels and tires that I've stored like this for several years and they're fine. The tires I've stored standing up all have had flat spots. |