Well, as usual, I don't know the answer, but I'm interested in what others have to say. I bought one of the last sets of Michelin Pilot GT's available, and they are stored in my basement, on an elevated plywood platform, flat on the side, in the cold and dark. They've been down there for some time now, and at my present rate of riding the Connie, I probably won't be needing them for two more years. If they aren't going to survive that long in that environment, then maybe I'd be better off selling them to someone who needs them now.