Mountain Snowflake Symbol

Winter Tires (Snow Tires)

Tires designed to perform on wet, cold, snow covered and icy surfaces. Tires carry the designation M+S, MS, M/S, M&S (Mud and Snow) on the sidewall and usually have 2-3 times the siping of conventional tires. They are designed to keep their operating features primarily at low temperatures and will deteriorate at higher temperatures. But they are not necessarily winter tires. The only icon that certify that they are indeed winter tires and have undergone specific and rigorous tests for winter conditions is the one with the mountain snoflake symbol.


Noticeably there is no provision in the definition for testing. To address this deficiency the Rubber Manufacturer’s Association and Tire Industry Association have agreed on a new standard that does involve testing called “Severe Snow Use.” Tires carrying this designation carry a snowflake icon next to the MS designation. These tires in addition to meeting the Rubber Manufacturer’s Association requirements must pass a test using an ASTM (American Society for Testing and Materials) testing procedure. These tires must attain a traction rating equal to or greater than the standard reference tire using the approved testing procedure.
Rubber Manufacturer’s Association Winter Tire Definitions for Passenger and Light Truck (LT) Tires;
  1.New tire treads shall have multiple pockets or slots in at least one tread edge that meet the following dimensional requirements based on mould dimensions:

  • Extend toward the tread centre at least ½ inch from the footprint edge, measured perpendicularly to the tread centreline
  • A minimum cross-sectional width of 1/16 inch
  • Edges of pockets or slots at angles between 35 and 90 degrees from the direction of travel

  2.The new tire tread contact surface void area will be a minimum of 25 percent based on mould dimensions.