For very long-term storarage, I would spray coat the outer tires and even the tread itself in spray Silicone.
Then, seal in BLACK plastic bags. Black will not transmit any light energy, whereas white bags or clear bags will. Evacuate as much air from the bag as possible, and then seal the open end.
Store in a cool an area, out of sunlight and heat. Like a basement area, or an under-house crawlspace.
When you eventually re-use the tires, be SURE to clean the silicone from the treaded surfaces !
JonB