Covering them does help. UV damages all tires be they winter or summer, on or off the car. As for temperature mine are kept in an un heated garage and no problems. Just raise them off the (concrete) balcony floor by whatever means and you are set. I use my stacked tires as a drink rest. ;)
2001 Focus ZTS 2004 WRX
"I'm just here for the camping"
http://www.facebook.com/profile.php?id=687620231
TEAM P.I.T.A. FTW!
"I'm just here for the camping"
http://www.facebook.com/profile.php?id=687620231
TEAM P.I.T.A. FTW!