How to Confirm a Winter Performer(Lea en español)
In 1999, The U.S. Tire Manufacturers Association (USTMA) and the Rubber Association of Canada (RAC) agreed on a performance based standard to identify passenger and light truck tires that attain a traction index equal to, or greater than 110 (compared to a reference tire which is rated 100) during the specified American Society for Testing and Materials traction tests on packed snow. The standard helps ensure drivers can easily identify tires that provide a higher level of snow traction, and tires meeting that standard are branded with the three-peak mountain snowflake (3PMSF) symbol.
A three-peak mountain snowflake (3PMSF) symbol branded on the tire's sidewall identifies tires that meet the required performance in snow testing.
Note: A Highway Safety Code regulation passed September 17, 2008 for Quebec, Canada, stipulates that: "Between 15 December to 15 March, the owner of a taxi or passenger vehicle registered in Quebec may not put the vehicle into operation unless it is equipped with tires specifically designed for winter driving, in compliance with the standards prescribed by government regulation. The prohibition also applies to any person renting out passenger vehicles not equipped with that type of tires."
Starting December 15, 2014, the Highway Safety Code regulation specifies only tires bearing the three-peak mountain snowflake symbol will be considered acceptable winter/snow tires in Quebec.
"A three-peak mountain snowflake symbol branded on the tire's sidewall identifies tires that meet the required performance in snow testing."
What's the difference in snow traction between M+S (Mud and Snow) branded tires from the past, modern all-season tires with M+S branding and a purpose-built winter/snow tire? While many drivers probably aren't absolutely sure, it can be the difference between getting to work, getting home or getting stuck.
The original definition of M+S tires is based on the geometry of the tread design. The M+S designation was first used to differentiate the knobby, bias ply tires intended for use on muddy and/or snow-covered roads from the straight rib tires used on early cars or trucks. Tires with tread designs that meet the definition may be branded with the letters "M" and "S" in several different ways (e.g., M&S, M+S, M/S, MS, etc.) at the discretion of the tire manufacturer.
When early radial ply tires were also found to deliver more snow traction than the straight rib, bias ply tires, the tire companies introduced all-season tires. Supported by advertising, all-season tires have presented an unspoken promise that they, throughout their life, can provide traction for all seasons...through spring's rain, summer's heat, fall's cooling and winter's snow. While this combined offering has made all-season tires popular, many drivers have learned that a geometric definition doesn't guarantee winter snow and ice traction.