Understand benefits of winter tires

Installing winter tires on passenger vehicles decreases costly collisions.

Canadian drivers lag in adopting winter tires in spite of evidence that their use saves lives and reduces road-accident injuries.

A 2011 study in Quebec shows that winter road-accident injuries dropped by five per cent there since winter tire use was made mandatory by law in 2008. Widespread use of winter tires is credited with preventing about 575 injuries per winter in the province.

These findings are supported by a new report from the Traffic Injury Research Foundation (TIRF) that concludes that winter tires decrease costly collisions. The report cites extensive research that shows that winter tires deliver superior traction, cornering and braking on all cold-weather road surfaces.

“All the evidence points to winter tires being the safest choice for driving in cold weather,” says Glenn Maidment, president of the Rubber Association of Canada (RAC), which represents tire makers. “Drivers should carefully consider whether winter tires are right for them and make an educated choice.”

This fall tire makers are urging motorists to get the facts about winter tires. A wealth of on-line information about the performance advantages of winter tires is available at the RAC’s website, www.rubberassociation.ca.

The TIRF report, entitled Winter tires: A Review of Research on Effectiveness and Use, stresses that the benefits of winter tires are not well understood and clarifies commonly held myths about winter tires.

Many motorists, for example, think that winter tires are only useful in regions with lots of snow. In fact, research shows that, once temperatures drop below seven degrees C, winter tires perform better whether the road surface is dry, snow covered, slushy or icy. Winter tires feature specialized rubber compounds that retain elasticity in temperatures below -30 degrees C and treads that grip at cold temperatures. In fact, winter tires deliver up to 50 per cent more cold-weather traction than all-seasons.

Another misconception is that all-season or summer tires provide sufficient traction in winter.

One of the most important advantages of winter tires is reduced stopping distance when braking. According to research cited by the TIRF report, at temperatures just below freezing on dry pavement stopping distance for vehicles with all-season tires can be as much as 30 per cent longer than for vehicles with winter tires. Winter tires have also been shown to have better traction on a snowy surface at -40 degrees C than an all-season tire has at plus four degrees C.

Some motorists avoid winter tires because their vehicles are equipped with Anti-lock Braking Systems, All-Wheel Drive or four-wheel drive. The TIRF report notes that these systems require sufficient traction to be effective and that winter tires provide that needed traction.

Another commonly believed myth is that two winter tires, rather than a set of four, is sufficiently safe. Mixing different types of tires creates a traction imbalance between the front and rear wheel positions and can cause a vehicle to “over steer” (when the winter tires are mounted on the front axle) or “under steer” (when the winter tires are on the rear axle). These unsafe conditions can make a vehicle difficult to control, particularly when cornering.

Proper tire inflation is also important during the winter-driving month. Tires that are under-or-over inflated have a smaller footprint on the road surface, which lessens their grip. The result is reduced stopping and handling capabilities and wasted fuel.

Tire inflation pressure can drop quickly during cold snaps. Every five degrees C change results in about one psi change in pressure, so a temperature drop of 15 degrees C would result in 10 per cent or three psi under-inflation. During winter, tire makers recommend measuring tire inflation frequently using a reliable tire gauge to ensure tires are properly inflated to the vehicle manufacturer’s recommendation.

“Motorists should also practice defensive driving and keep their vehicles properly maintained and prepared for winter driving,” says Maidment.

When buying winter tires, motorists should look for the mountain snowflake symbol on the sidewall. Tires with this symbol meet or exceed tire industry snow traction requirements.

www.rubberassociation.ca.