What is the best way to store tires? what would be the optimal temperature? standing up or laying down? is there anything to treat them for longevity so the rubber dose not dry rot or crack? inside or outside? humid or dry air?

 

Protect them from the sun in an indoor environment and they will keep for quite a while, unless you're talking about storing them for 20 years or something...

 

stacked in a cool and dry location. vacuum packed is ideal. no treatments.

read more:
http://www.tirerack.com/tires/tirete....jsp?techid=37

 

If you are storing them on concrete, get wood between the tires and the concrete. Concrete will draw the moisture out of the rubber causing dry rot.

 

no where near electric motors. ozone rots tires

 

Fluorescent lights also produce ozone and will crack out your tires over time as well.

 

Put them in trash bags or wrap them in plastic. Garage, shop, or anywhere indoors. no treatment. People might tell you to put armor all or wet tire shine on, but those only dry rot your tires unless you apply every week.