I have several extra tires, two on a spare wheelset, and others in a bundle. I am not riding as much as I was a year ago, so I will not be wearing out tires as fast as I was.

What is the best way and conditions to store these tires so that the rubber doesn't just crack and split when I put them on wheels and pump them up?

Note: I don't know if it makes a difference, but I live at about 5000' of elevation in a very dry climate; forced air heating is used in my apartment about 6 months a year.