My winter tire education began on a cool fall day in the 1960s, when my father took me to the garage and handed me a jack and a lug wrench. Falling leaves drifted down past the open door as my dad slipped on his work gloves to help me raise the car. Until then, my knowledge of tires was limited to three obvious fundamentals: they were round, they were black and they kept the car off the ground. My father was about to teach me what kept a car stuck to the earth when the weather turned cold.
I’d always noticed that my dad could make it up hills where others couldn’t, and that while others spun, crashed and slid into the ditch, we’d always kept going and made it home safe. How was that?
My father pulled away a blue tarpaulin to reveal a set of freshly painted steel wheels, each mounted with a winter tire. As we torqued the new wheels onto our Mercury, my father began his lessons on tire technology and the art of winter driving.
“It’s not going to snow for a few weeks,” he told me. “But you can’t wait for that – summer tires don’t work in the cold.” Then he explained why it was foolish to use only two winter tires [like most drivers did back then]: “Two wheels do the acceleration,” he said. “But that just gets you into trouble. Once you’re moving, all four wheels have to do the braking and cornering.”
My father died 14 years ago, but his teachings were the beginning of a lifelong education. The key point: winter tires really work. Not using them is like driving a car without seatbelts – you’re passing on a critical safety feature. The value of winter tires has been driven home by my own testing, consultation with experts and by statistics: in Quebec, where they have been mandatory since 2008, winter collisions have fallen by 17 per cent, and crashes causing serious injury or death are down 36 per cent.
Exploring winter tire technology can be a druidic quest (amazingly, not everyone gets excited as I do about siping, hysteresis and angular momentum). So we’re going to boil down a catalogue of knowledge into a primer that compresses the knowledge of countless people I’ve met over the years – engineers, mechanics, driving instructors, ice racers, tire designers, chemists who design rubber that can stick to ice and, of course, my long-departed dad – the guy who never crashed.
The collected wisdom
1. All-season tires are a bad compromise. On snow, ice or cold pavement, the stopping distance of a car with winter tires can be up to 30 to 40 per cent shorter than one with all-seasons. Since the force of a crash increases as the square of impact speed, this could be the difference between life and death.
2. Although it’s the treads that you notice, the most important part of a winter tire is actually its rubber compound, which is designed to stay soft in freezing temperatures. Like a gecko climbing a sheet of glass, a tire sticks to the road by conforming to minute imperfections. The soft rubber treads of a winter tire are able to splay and wrap themselves around minute protrusions on cold pavement, or even on what may appear to be perfectly smooth ice. Summer tires, which are designed to operate in warm temperatures, harden as the temperature falls. All-seasons, which must be designed for year-round use, cannot match winter tires in low temperatures.
3. Premium winter tires perform better than basic models. What you’re paying for is the latest in rubber technology and tread design. What you get is traction that may be up to 15 per cent better than economy-model winter tires. (If you want to see the difference between different grades of winter tires, go to an ice race. “The drivers with the premium tires are all out front,” says Ontario racer and winter driving instructor Ian Law. “There’s no comparison.”)
4. It’s about temperature, not snow. Winter tires should be installed when you expect temperatures to fall to 7 C or below. As the temperature falls, the rubber in summer and all-season tires becomes inflexible, killing traction. Watch the thermometer and use common sense, because no one will tell you exactly when to put on snow tires (unless you live in Quebec, where the law dictates that your car be equipped with winter tires between Dec. 15 and March 15).