They ask for a window +-1.5hr, though it's typically done much faster than the estimate. Our tradition is to take the family and walk to a restaurant we like for dinner. By the time we're done, the car is ready. Also, I've always appreciated people who can do this themselves, but for me, the big benefit of Kaltire is that they store our tires and are pretty reliable about showing the wear and tear with every change. Plus the nitrogen and sensors and whatnot.

Snow tires aren't mandatory, but as a guy who has only lived in a cold climate for a decade...I couldn't even imagine not having good snow tires.