5. Winter tires should be narrower than summer models. Experts recommend that you go down one or two sizes when installing winter tires – if you car came with 215-millimetre wide summer tires, for example, your winter tires should be 205 mm or 195 mm. Reducing the width of a tire increases the pressure it exerts on the surface beneath it – this helps the tire slice through snow and reduces hydroplaning.
6. Winter tires are designed to move water. When a tire presses down on snow or ice, it melts the top layer, creating a thin film of water (the same phenomenon that occurs as a skate glides across a rink). If the water isn’t moved away from the area in front of the tire, the car will hydroplane. This is why winter tires are covered with grooves (including tiny channels known as “sipes”) that move water away to the sides, allowing the tire to stay in contact with the surface.
7. All-wheel drive helps you accelerate, not stop. On slippery surfaces, vehicles with four driving wheels can accelerate better than those with two-wheel drive. But their cornering and braking capabilities are little different than a two-wheel-drive model. When you’re trying to stop or turn, the limits are determined by the traction capabilities of your tires, not the number of driven wheels.
8. Black ice is not a death sentence. Good winter tires can stick to glare ice, but only if they are within their traction limits. If your car begins to slide, look straight down the road to where you need to go, and maintain a light grip on the wheel. As the car decelerates, you will gradually regain control as the tire’s rubber begins gripping surface imperfections on the ice. Slow speed and gentle control inputs will maintain traction.
9. The performance of winter tires has been significantly improved over the past decade by advanced rubber compounds that allow designers to make tires softer without sacrificing other critical properties, including wear and heat buildup as temperatures climb. Major manufacturers spend a lot of money on R&D. Jaap Leendertse, winter tire platform manager for Pirelli in Milan, Italy, told me the company has developed more than 300 compounds in the ongoing quest for the ideal winter tire.
10. In the old days, winter tires came with deep, aggressive treads designed to paddle through deep snow. This made for a noisy ride and compromised stability, since the treads deflected under acceleration, braking and cornering loads. Current winter tire technology focuses on shallower treads with closely spaced grooves that carry away the water film created when the tire presses down on ice or snow.
11. Although testing makes it easy to see the performance advantages of a winter tire (you stop faster), the technology behind it is deceptively complex. Tire designers must consider a long list of factors, including tread stability and hysteresis (a process that generates heat as a tire repeatedly deforms and recovers as it rotates under the weight of a car).
12. Although they offer an advantage on glare ice, studded tires are far less effective than non-studded models on cold, bare pavement (where most drivers spend the majority of their time during the winter months).
13. Some manufacturers offer winter tires that use rubber mixed with hard materials (like crushed walnut shells and chopped nylon strands) to give increased bite. Although these can offer improved traction in some conditions, the most important factors in a winter tire’s all-round grip are the quality of its rubber compound and its tread design.
14. Although it’s not recommended for everyday driving, reducing the air pressure in your tires can help you gain in an emergency. Reducing tire pressure increases the tire’s contact patch, and may help you make it up an otherwise impassable icy grade, for example. Bear in mind that this is an emergency technique only, and will reduce overall control of your car by making the tire carcass less stable. Unless you’re stuck at the bottom of an icy hill with no other option, you should use the inflation pressures recommended by your car manufacturer. If you do lower tire pressures to make it out of an emergency situation, drive slowly and reinflate the tires to the recommended pressure as soon as possible.
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