initial D is REAL!

Hey guys. I have 2 255/40/17 kuhmo mx tires that ended up getting a flat spot on them when i slid out of control. They have a good amoutn of tread left so I want to save them for a drift day or soemthing. They are already dissmounted. Is there anything I can do to help them last longer? They are sitting in my garage.
How long do you think they would last for? I'm not 100% sure how old they are, but they have about 50-70% tread left

Black91n/a

Keep them in some garbage bags in a cool, dry place. Keep them out of the sun, out of the cold and away from sources of ozone.

initial D is REAL!

ill put trash bags on them ASAP. Thanks