Hi, I would read this from TireRack on flat spots. The new high performace low profiles have a compound that will flat spot if not stored correctly. At a $1000+ a set I would do somthing when storing them to prevent flat spots. I have heard from 8-10 layers of carpet to $300 on a pad that will prevent them. If we are storing for a very long time we take the tire off and store them.
http://www.tirerack.com/tires/tirete....jsp?techid=42