October 31, 2005

Special Feature:
Michelin winter tire test
By Jil McIntosh
Discuss this story in the forum at CarTalkCanada

Photo: Michelin. Click image to enlarge

It's a no-brainer: winter tires work better in inclement weather than all-season tires do. But it's important to know why, and exactly how much better, and to that end, Michelin recently invited journalists to an arena in north Toronto to ride along on the ice.

The vehicles were identical Toyota Matrix compact hatchbacks. One was clad with Michelin Energy MXV4+ all-season tires, the other with the company's X-Ice winter-specific tires. Two race drivers, Richard Spenard and Sylvain Champoux, were my chauffeurs, seemingly indifferent to the chilly conditions on the ice pad and more than willing to answer even the most basic questions.

At one time, drivers routinely changed tires in Spring and Fall, swapping summer tires for snows. Tire technology has come a long way since then, and almost all new cars are now sold with all-season tires. They're a good product, but they're a compromise, and there's a reason why serious drivers call them "three-season" tires.

Rubber tends to become soft in hot weather, and hard in cold temperatures. Problem is: that's the opposite of what you want. A good summer tire will stay firm in hot weather, to maintain integrity; a winter tire is softer, so that it will be better able to grip the pavement. Tread patterns are also exclusive to each type.

An all-season tire is basically halfway between the two, but because it's got to perform well in hot weather, it isn't the optimum choice for colder conditions. That's why it's a good idea to use all-seasons for three seasons, and switch to a good winter tire in the Fall.

"Here in Canada, we have severe conditions, so we need four winter tires," says Nadine Lussier, Michelin's communications manager. "(All-season) compound loses flexibility below seven degrees (Celsius). That's not that cold. It loses grip, acceleration power and braking, even on cold, dry pavement."

Richard Spenard and Sylvain Champoux at the Michelin X-Ice Winter Driving Event. Photo: Jil McIntosh. Click image to enlarge

Many drivers believe it's only necessary to put winter tires on the driving wheels, but that's a misconception, Richard Spenard says. "You could use two back in the days, thirty years ago, when they installed snow tires," he says. "Now, winter tires are for the cold climate, not just snow. Using two instead of four unbalances the car, and it could even be dangerous, because one end sticks more than the other. The adhesion is different from front to back."

The drivers took me through four tests: acceleration, braking, slalom and obstacle avoidance. The acceleration test was a drag race of sorts, with both cars starting from the same point. At 20 km/h, the car equipped with winter tires finished about a length and a half ahead; sitting in the all-season car, I could feel the tires slipping as they struggled to grip the ice.

The Toyota Matrix in the brake test segment. Photo: Jil McIntosh. Click image to enlarge

The brake test simulated a panic stop, against a row of cones marked with distances and a radar device to measure our speed. Naturally, the size of the ice rink kept everything to a sedate 20 km/h, but it still took 11.5 metres to stop with the winter tires. With all-seasons, at the same speed, the distance was 13.5 metres. That can be the difference between stopping safely, and running into someone's trunk, especially at higher speeds.

The slalom event was next, and through the cones, Sylvain Champoux was able to reach 13 km/h while still maintaining enough traction to finish the course; with the winter tires, he reached 16 km/h, and reported that the car was easier to drive and more predictable in its handling.

The Matrix going through the slalom portion of the test. Photo: Jil McIntosh. Click image to enlarge

The final test, obstacle avoidance, required him to drive toward a cone, hit the brakes at a predetermined spot, and then manoeuvre safely around the obstacle. With the all-season tires, Champoux smacked the cone the first time out; his best performance while avoiding it completely was 21 km/h. With the X-Ice tires, the final speed was 23 km/h. That doesn't sound like much, but it's a ten per cent improvement – and try to remember the last time you drove down the street at only 23 km/h. "All of these were low-speed manoeuvres," Champoux says. "Remember that they will all be exaggerated at higher speeds."

It's also true that most of us don't spend all winter on a smooth ice pad, but glare ice is a winter reality, and grip and handling can be compromised even on dry pavement if it's cold enough to harden the tires.

"People depend on ABS and ESP, but different adhesion rates can affect the car's computer," Champoux says. "With winter tires on the front and all-season on the rear, the back end wants to come around. ABS and ESP are only as good as the tires on the pavement. People think their traction control replaces winter tires, but it does not. You need good tires to cope with winter."

Visit our winter driving section ....

Jil McIntosh's automotive work and her garage includes cars both old and new; she writes for The Toronto Star Wheels, Old Autos, and Canadian Street Rodder.