Dear Tom and Ray:
I live in Toronto and have a Chevy Tahoe that I only drive 7,000 miles a year. I obviously need winter tires for at least six months a year. I'm wondering if there's any reason I can't just buy winter tires and leave them on all year long. I don't care if the ride is noisy and rough. I just don't want to bother with changing my tires twice a year if I don't have to. Do I have to? -- Larry
TOM: Sadly, yes, Larry. You have to change to summer or all-season tires during warmer weather.
RAY: Noise isn't so much the issue anymore, as snow tires have gotten a lot quieter. The issue is the rubber compound. The rubber used in winter tires is designed to stay soft and pliable in cold temperatures -- from, say, 0 to 40 degrees Fahrenheit. Staying soft allows them to conform to whatever's on the road, and give you a better traction footprint in snow and ice.
TOM: But when the weather gets warm, winter tires get too soft. That creates two problems. One is that they wear out very quickly. So if you keep them on all summer, you'll burn through $400 worth of snow tires in no time.
RAY: The second problem is that your handling is compromised in warm weather. Imagine if you need to make an emergency maneuver, and your tires are kind of soft and squishy. You're not going to get the kind of crisp handling that you need in order to avoid that oncoming sausage delivery truck.
TOM: So, if you live in a place where you need winter tires for part of the year, you really have to replace them in the spring with something better suited to the warm weather. Or you have to move somewhere that's cold in the summer, too. Like the North Pole. Or San Francisco.