There are two common grading systems for tires to help identify winter tire traction capabilities. All tires that pass certain winter tire traction tests can be marked with a symbol molded onto the side of the tire. One is the M+S (mud and snow) symbol, and the second is the Mountain/Snowflake symbol. Both are based on standardized tire industry testing, however the extent of testing, and the traction levels required to qualify for each symbol are very different. While both symbols are helpful indictors of what you can expect from the tire, it is important to understand the difference between the two. This is particularly important when deciding on which tires to purchase for your car, SUV, CUV or light truck in Northern climates.
M+S Tire Marking on All-season Tires
The M+S tire marking system was first introduced to differentiate knobby bias-ply tires from the more common rib treads on early radial car and light truck tires. Over time, M+S became a standard marking to show the tire had some “all-season” capability compared to summer tires. Unfortunately, it is a very one-dimensional test in that it only measures traction in packed snow and mud. It does not measure traction on ice, or traction on cold dry roads. For that reason the M+S Symbol falls short in helping fully evaluate winter tire performance expectations in winter driving conditions.
Mountain/Snowflake Symbol – Severe Snow and Winter Traction
Recognizing a need for a more up-to-date and helpful measurement of true winter performance, as well as a way to differentiate all-season tires from winter tires, the Rubber Manufacturers Association (RMA) came up with the Mountain/Snowflake symbol for tires. When you see this icon on the sidewall of your tire, you can be assured it meets more stringent winter traction performance requirements. This includes snowy, slippery roads and low temperatures. Most all-season tires do not qualify for the Mountain/Snowflake symbol because the tread rubber in all-season and summer tires become hard at temperatures below 40 F. Only dedicated winter tires, some all-terrain light truck tires, and some of the latest generation “all-weather tires” meet the traction qualifications for the Mountain/Snowflake symbol’s severe snow service rating. One “all-weather” tire with the Mountain/Snowflake symbol is the Nokian WR G3 tire. The Nokian WR G3 are tires that you can leave on the vehicle all-year round, and still be assured of good traction in winter conditions other than just light snow. Nokian also makes a full line of winter tires for all vehicles and their new Hakkapeliitta 9 studded tire is a great choice for severe weather conditions.
Do I Need Tires with the Mountain/Snowflake Symbol?
At this time, there are only a few areas in North America were winter tires are mandatory. In some Canadian provinces, only tires bearing the Mountain/Snowflake symbol are considered acceptable winter/snow tires, and by law must be used from October through March. Winter tire usage laws are under consideration for some northern U.S. states as well, but for the time-being, good all-season tires that carry the M+S symbol continue to be the broader definition for the minimum acceptable levels of winter traction. M+S rated tires or snow chains are usually permitted in mountain passes and other areas under winter weather advisory conditions.
Regardless of the local laws and regulations, winter tires are proven to increase safety and reduce accidents if you regularly drive in snow, slush, ice, or cold conditions, or live in an area that regularly experiences winter temperatures below 45 degrees. Visit Tires-easy.com to find all your winter/snow tire needs or check out another helpful post, Buying Tires Online – What to Know.