Just my experience and kind of a tangent but I've never needed an appointment to get a tire swapped. I've found that if you're willing to take off your own wheel and you're traveling that most shops will find a way to squeeze you in. Usually I'm out within a hour after I ride up out of the blue.
I've done it in:
Bangor, Maine - Yamaha dealer
Butte, Montana - Harley and other brands shop
Salt Lake City - Generic shop
Sna Rafeal, CA - Ducati shop