You all raise a good point about icy days versus other days. For this reason, I keep my studded tires mounted on their own set of wheels. This way when we've got decent weather, I just swap out the wheels. I've only been caught once in a commuting situation with the wrong wheels. When I went to work the weather was great. During the day we got hit was an unexpected snow shower. That ride home was a bit more skittish, but made it safely.