Im curious if used tires lose any integrity or have any problems if they sit in a garage for years. Do they dry rot or anything? how can you inspect and tell if they are ok?

 

There's a Tire Rack article that covers the subject. Their conclusion is that "street" tires are good for 6-10 years. One thing that will cause accellerated damaged is exposure to ozone. Having a large electric motor in your garage (e.g. - air compressor) can generate increased ozone levels.

http://www.tirerack.com/tires/tirete...jsp?techid=138

 

my car has been sitting on michelin ps2's for 2 years and haven't had any issues but it concerns me greatly. i will use them this spring if i have to buy a thirdgen to put them on.

 

I beleive it was Europe that has expiration dates for tires, this is what I could find in a search. Some more to consider.
http://www.cbsnews.com/stories/2005/...in698335.shtml
http://www.keprtv.com/news/19692654.html

 

Just to be clear, electric motors only generate ozone when they're running.

Two years should be no big deal, unless the tires were already several years old when you put them away.

 

If you store the tires in a plastic bag and a cool, dark area it helps too. It keeps the oils from evaporating from the rubber.