Skiers can easily relate to the decision-making process in purchasing winter tires. Just as all-mountain skis can handle any snow condition and terrain fairly well, all-season tires can suffice for any road condition. However, as any skier on all-mountain skis knows after watching a smiling buddy on powder skis blow by on a waist-deep day, there is a big difference between sufficient and ideal.
HISTORY OF WINTER TIRES
Until about 30 years ago, switching the family truckster to snow tires was a seasonal rite-of-passage for those in colder climates. The advent of all-season tires turned this ritual into a “back-in-the-day” story for granddads. All-season tires are now standard on most cars, trucks and SUVs. Nonetheless, snow tires, or “winter tires” as the manufacturers more accurately call them, are still sold for cold-climate markets.
According to Sachin Deshpandé, public relations manager at Michelin, the reasoning for the “winter tires” moniker stems from a distinction based solely on temperature, rather than snowfall. Across the industry, the benchmark of 7 degrees Celsius, or about 45 degrees Fahrenheit, is the magic number for winter tires. The rubber in all-season tires starts becoming more rigid below that line, so traction suffers.
WINTER TIRES TODAY
Costing about the same as all-season tires, winter tires should be bought in a set of four. Drivers would sometimes switch out just two tires “back-in-the-day,” but today’s designs make that practice unsafe. Owning two full sets of tires obviously requires more of an initial investment, but the long-term cost tends to even out with each set being used for only part of the year.
The M + S (“mud and snow”) designation on the sidewall of most SUV tires does not necessarily denote a winter tire. A true winter tire has an additional symbol—a snowflake inside a mountain. Tests by Car and Driver suggest that winter tires are more important than four-wheel drive for control in braking and turning. Four-wheel drive largely translates into better acceleration on snow and ice, not necessarily better stopping. In fact, better acceleration leads to driver overconfidence which leads to the remarkably common sight of four-wheel-drive SUVs in roadside ditches.
“It’s great to have four-wheel-drive, but imagine driving a four-wheel-drive on a bald tire, a tire that does not have any tread at all. Four-wheel-drive is not going to be of much use,” Deshpandé says. “At the end of the day, all the technology touches the ground in four patches that are about the width of your palm. That is the tires. The tire’s tread and its compounding are absolutely crucial for the capability of the four-wheel-drive.”
COMPOSITION OF WINTER TIRES
To achieve better grip in cold temperatures, winter tires are made of softer rubber compounds. Wearing more quickly on dry, warm pavement, the softer rubber makes winter tires an impractical choice for year-round use. Speaking of wear, three or four winters is the usual life expectancy for most winter tires. The brands tout various additives designed to increase grip and bite. Toyo Tires, for example, puts tiny bits of walnut shells in its winter-tire rubber.
Tread design, the other major distinctive feature of winter tires, attacks the problem of snow and ice. Small tread blocks and plenty of sipes, thin cuts in the tread, are typical traits of winter tires. For really serious snow and especially ice, studdable tires have optional metal studs dotting the tread surface. Studded tires can really cut into the ice for traction. Unfortunately, they also cut into dry asphalt. Looking to avoid higher road-maintenance costs, many U.S. states and Canadian provinces prohibit them during all or part of the year. (list of laws here)
WINTER TIRE CATEGORIES & MANUFACTURERS
Winter tires are generally grouped into three categories: winter performance, studless winter and studdable. Winter performance tires address the rubber temperature issue to excel on wet and dry pavement in cold weather. However, in particularly heavy snow and ice, they’re less suitable than regular studless winter tires—and certainly less than studdable ones.
Most tire manufacturers offer winter tires of each sort. Bridgestone Blizzak and Michelin X-Ice are a couple of the well-known lines. Nokian, a Finnish company claiming the first winter tire in 1936, has a cult following for its outstanding—and pricey—winter tires.
Skiers and riders know the right gear can make a difference on the slopes and may want to consider the right gear for winter roads. After all, getting to the mountain safely is the first order of business on a powder day.