M+S and 3PMSF are ratings that indicate a tire’s capabilities in various weather conditions. M+S tells that a tire is suitable for “Mud” and “Snow” traction, and this symbol is only awarded to tires having 25% voids/grooves to tread ratio. The 3 Peak Mountain Snowflake (3PMSF) rating on the other side, is given to tires having superior snow capabilities, where their all season compound is very thermal adaptive, as it can handle temperatures below 40° Fahrenheit.
M+S basically is the older standard for snow, and its still used now. Though its not the most accurate, as it judges how a tire is no snow and mud (mostly snow), by just looking at the grooves and not actually measuring the traction values. The 3PMSF rating on the other side, is awarded to tires which have at least 10% better acceleration compared to average all-season tires. So this rating is much more accurate.
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M+S Rating
M+S rated tires have a tread pattern that is optimized for better traction on mud and snow, to be more specific soft muddy and snowy terrains.
And only tires with grooves can handle it. That’s why all M+S rated tires have at-least 25% of their tread dedicated to grooves.
But why grooves are so significant here? Well let’s divide this section in to mud and snow traction.
Mud Traction
Surviving on this terrain, you need faster mud evacuation through the tire. And that is only possible with grooves.
That’s why tires having less tread voids, aren’t able to escape the thick material in time, causing “mud packing”. And a packed-with-mud tire has no friction with the ground. It just slips on it’s place.
For your Info: Almost all of the A/T tires are rated with both of these ratings, as they are great on snow.
Snow Traction
Winter traction especially on fluffy snow is also dependent on grooves, as they grab snow particles and lodge them in to make snow to snow contact.
Snowflakes have an interlocking pattern of their own, and they stick with each other effortlessly. That’s why the stuck snow in the grooves provide better friction with the ground, compared to rubber to snow contact.
3 Peak Mountain Snowflake Rating
The 3 peak mountain snowflake (3PMSF) symbol was established in 1999 by the U.S Tire Manufacturers Association (USTMA) and the Rubber Association of Canada (RAC), combined.
This symbol is awarded to tires which can pass certain severe snow traction tests which tell how well they accelerate on ice and hard packed snow. (The symbol can be found on sidewalls).
The tires eligible for this rating attain a traction index equal to, or greater than 110 during specified American Society for Testing and Materials traction tests on packed snow.
To put it in other words, it tells us that the 3 peak rated tires have at least 10% better acceleration capability compared to average all-season tires.
It’s important to keep in mind that the 3PMSF test only measures a tire’s acceleration traction on medium-packed snow, braking and turning on snow, along with ice traction are not components of the test.
Note: While 3PMSF-branded all-season and all-terrain tires are expected to provide improved snow traction beyond a standard M+S branded all-season tire, they cannot match the traction of dedicated winter/snow tires in all winter weather conditions and should not be considered as a replacement for where and when a dedicated winter tire is needed.
Also Note: It is important to note that 3PMSF rating symbol is only valid for tires that are made for specific EU, Canada and US market.
Summary
while tires that have the 3 Peak Mountain Snowflake (3PMSF) rating symbol may provide better traction in snowy conditions than tires that have only the Mud and Snow (M+S) rating symbol, they are not as capable as true winter tires in all types of adverse weather conditions.
The 3PMSF rating symbol indicates that a tire has passed specific tests and is designed for use in severe snow conditions. Tires with this rating are typically labeled as “winter tires” or “snow tires” and are made from a special rubber compound that remains flexible in extremely low temperatures.
On the other hand, the M+S rating symbol is based on the tire’s tread pattern and the materials used in its construction, it indicates that the tire has a tread design that is optimized for better traction on mud and snow and generally considered as all-season tire.
