Along with all of the numbers printed on your tires, if you see a 3-peak mountain snowflake symbol, your tires are good to go for serious winter driving conditions. Here is the history and meaning behind that curious symbol.

What Is the 3-Peak Mountain Snowflake Symbol?

The 3-Peak Mountain Snowflake Symbol (3PMS for short) is a six-pointed snowflake inside a three-peak mountain, found on tires that meet specific standards. They signify the tire has been tested for acceleration on medium-packed snow. Braking and turning don’t factor into the testing.

Tires with the 3PMS symbol have scored at least 110 on the traction index. This means they accelerate at least 10 percent faster than a typical all-season tire that isn’t 3PMS rated. (There are all-season tires that have the 3PMS designation.)

The U.S. Tire Manufacturers Association and the Tire and Rubber Association of Canada developed the 3PMS symbol in 1999. Tire manufacturers are required to meet the standards for the 3PMS symbol in the U.S., Canada and Europe.

Tires with the 3PMS are typically made of a softer rubber that won’t harden in sub-freezing temperatures. These tires also have a particular type of tiny cut across their surface called siping. This improves traction on snow and ice.

Paul Ulibari, general manager of Colorado Tire and Service in Denver, says there’s no substitute for 3PMS tires during a winter storm in the Rockies. “They just don’t compare,” he says.

Where Is This Symbol Found?

“The symbol is on the sidewall, and it’s very distinct,” Ulibari says.

He also notes customers often confuse mud and snow tires with 3PMS tires because of the former’s size and knobby design. Mud and snow tires will have an “MS” symbol on their sidewall. “People think the bigger and badder the tire looks, the better it’ll do in snow,” Ulibari says. “But that’s not actually the case.”

Are Some Cars Required To Have 3PMS Tires?

In British Columbia and Quebec, drivers must have 3PMS tires on their cars from December to March. During winter storms, Colorado also enforces a traction law that requires drivers to use tires with a tread depth of at least 3-1/16-in. and the 3PMS symbol.

What Other Information Can Be Learned From the Symbols On Tires

Beyond the 3-peak mountain snowflake symbol, other tire symbols provide insightful information, including:

  • Tire size: the tire’s dimensions,
  • Load index: its maximum weight capacity,
  • Speed rating: its maximum safe speed, and
  • DOT code: its manufacturing date and compliance with U.S. safety standards.

The first letter indicates the type of tire. “For example, ‘P’ means it’s a passenger tire and ‘LT’ means it’s a light truck tire,” says Duane “Doc” Watson, a technical trainer at Bosch Mobility Aftermarket.

After those letters, you’ll find a set of numbers indicating the load index and speed rating. Speed ratings range from A1 to Y, and the letter following the speed rating indicates the tire’s construction. “R” is for radial, “D” is for diagonal and “B” is for belted bias.

After tire construction, the next two numbers indicate the wheel diameter, such as “15, which means the tire would fit a 15-inch diameter rim. Beyond all of those, tires can include other markings, which indicate whether they’re tubeless or what tube type they require.

“Additionally, ratings for tread wear, traction and temperature indicate the tire’s expected lifespan, grip capability and heat resistance,” says Justin Dugan of American Trucks. “Some tires also feature rotation direction and inside/outside labels, especially if they are directional or asymmetric, which helps ensure optimal performance.”

However, not all of the symbols are standardized, says Chris Pyle, an auto expert with JustAnswer. “It would be best to look at the brand, name and size and then compare them online to see how they review for different driving scenarios,” he says.