It's normal to think that since you have an all-wheel drive equipped car and a set of all-season tires mean that you can conquer the world. I mean the words "ALL" and "WHEEL" and "SEASON" pretty much covers everything you need, right? WRONG!
As an automotive enthusiast, and living in an area where snowy weather can be at times awful, we know in general that all-season tires are not suitable for winter or icy driving. However, do we really know the reason why summer and all-season tires don't work as well during the winter time?
Tirerack.com and Michelin flew me out to the University of Notre Dame for their Winter Driving Experience to learn about all-season tire use in the winter, and to also learn about Michelin's new winter tire, the Michelin X-ICE XI3.
Full disclosure, I was wined and dined by these wonderful people so I can learn and tell all of you, that depending on where you live in the US and the rest of the world, you might be making a big mistake if you're relying on all-season tires all year round. Just take a look at this chart below:
The reason why winter tires work much better in the colder temperatures has a lot to do with the concept of Glass Transition Temperature. It's the temperature where polymers, like your tires, go from a rubbery and pliable state to a more brittle and hard form. Thanks to the added silica within the winter tire formula, the glass transition temperature of a winter tire is much lower than a summer and all-season tire. This allows the tire to stay more compliant to the colder road surfaces during the winter months.
Just like how racecars need their tires to warm up to provide more grip, winter tires need to be pliable to provide more grip. In fact, it is advised that if you consistently cross below the 44 degree temperature threshold, you would be a candidate for a winter tire set.
Winter tires also have a different architecture that allows for better grip on slushy, snowy, and icy roads. Features like sipes, tread blocks, and micro-pumps help deliver better traction on dry, wet, and wintry roads, while all-season tires only have tread designs that help with wet and dry conditions only.
As further proof that all-season tires are somewhat hopeless in the winter time, I sat behind both a front-wheel drive and an all-wheel drive car, each one had a version equipped with all-seasons and winter tires. Each one of these cars were tested in University of Notre Dame's Compton Family Ice Arena to simulate the worst winter driving condition: Icy roads.
Winter tires' biggest deterrent might just be the cost itself. The cost of maintaining a second set means buying new wheels and tires, and the hassle/cost of mounting the set on and off a couple of times a year. However, if you look at the economics from a more macro level, the cost of maintaining a winter set is actually not that much more expensive than maintaining a single set. That's because with an added winter set you actually have TWO sets of tires. That reasoning might sound a bit obtuse, but the fact that you're utilizing two sets means you're spreading the wear and tear across more tires.
Relying on a single set of tires, like all-seasons, mean that the rate at which you're wearing down the tire requires you to purchase your second set of tires a bit earlier. Whereas when you maintain an additional winter set, that secondary set buying activity is pushed up earlier.
In the least, buying a winter tire set should be seen as an insurance and protection against loss of driving control. As seen in the video above, all-season tires can be completely hopeless during icy road conditions. For more information, checkout tirerack.com at the link here.