Thanks. I actualy got the idea from Tire Rack and I'm just asking the Saab experts here about them.
I have occasionally thought about getting a spare set of rims for my other tires, but it's always seemed to me that it would only make financial sense if I could get them really cheap at a junkyard. The price at Tire Rack was over $100 per tire, and I would never make that up in saving changeovers.