When a consumer wants a tire able to handle severe snow in extreme cold—a winter tire—all they have to look for is the Three-Peak Mountain Snowflake (3PMS) logo.
The symbol was adopted two decades ago to set winter tires apart—for safety—from the rest of the growing crowd of high-performing tires, which included the all-season and all-weather categories.
"In the 1990s, Canada became the focal point of the global tire industry, and policy makers concerning the link between tires and winter driving safety," a spokesperson for the Tire and Rubber Association of Canada (TRAC) said. "The issue came under scrutiny following a vehicle collision that was linked directly to the vehicle being equipped with tires not suitable for winter driving."
The symbol—a snowflake inside of a three-peaked mountain—indicates the tire meets performance-based standards for safety in severe snow conditions.
"The tire industry and policy makers in North America recognized the need to classify tires designed for winter driving and developed a voluntary performance-based standard for winter tires—the ASTM F1805 Traction Test," TRAC said.
Tires are tested for acceleration on an average snow-pack and, basically, must accelerate 10 percent faster than an all-season "reference" tire. The tests do not measure braking or turning in snow, deep snow response or ice traction.
The 3PMS symbol is in addition to the M+S (mud and snow) symbols used on snow and all-season tires. The M+S definition is geometric-based on tread, while the 3PMS definition covers tires that attain a traction index equal to or greater than 110 percent during the ASTM F-1805 snow traction test devised by ASTM International.
Today, tires in other categories, like the all-weather Goodyear Assurance WeatherReady and Michelin's all-season CrossClimate2, have attained the 3PMS symbol.
"The symbol means the tire has been tested by the manufacturer to perform in severe snow conditions," according to a Michelin official. "Any Michelin tire with 3PMS has undergone severe snow traction testing and has been determined worthy of the designation."
The voluntary initiative was announced Feb. 1, 1999, by the Rubber Manufacturers Association (now the U.S. Tire Manufacturers Association, or USTMA) and the Rubber Association of Canada (now TRAC).
"This new standard will ensure that Canadian consumers can identify and purchase tires designed to provide a higher level of traction in Canada's harsh winter conditions,'' then-Transport Canada Minister David Collenette said in 1999.
The RMA and RAC worked on the new definition for about 2 1/2 years, after Transport Canada (Canada's counterpart to the U.S. Department of Transportation) requested it.
The ASTM standard spells out how to set up ice and snow surfaces—including precise definitions of four types of snow—and how to conduct the test. The traction index is derived by measuring wheel slippage of the driven wheel versus that of the non-driven wheel.
Each test consists of 10 runs over the prepared course, with traction values determined by averaging eight valid test runs out of 10, according to the ASTM standard. Each candidate tire is to be tested at least three times, preferably on different days.
The 3PMS symbol also has become important in areas where winter tires are a requirement, like Canadian provinces Quebec and British Columbia.
According to Quebec's highway safety code, only tires with the 3PMS symbol are considered winter tires. Since 2007, by law, drivers must use winter tires from Dec. 1 through March 15.
At the time of making the law, Quebec transportation officials found that while only 10 percent of drivers didn't have winter tires on their vehicles, 38 percent of fatal and serious winter accidents included a vehicle without winter tires. After the law was initiated, officials in Quebec found—in a 2011 study—that mandatory winter tires resulted in a 5 percent decrease in serious crashes and a 36 percent decrease in fatalities and serious injuries.