Look at the sidewall of a tire claiming any kind of winter capability and you'll find one of two markings: M+S (mud and snow) or the 3PMSF (three-peak mountain snowflake). They look similar in marketing but mean very different things.
M+S — almost meaningless
The M+S marking dates to the 1970s. It just means the tire has a tread pattern with some snow capability — based on geometry, not performance. The tire isn't tested for actual snow grip; it just has to look like a snow tire. Every all-season tire has the M+S marking. Most can't actually drive in snow.
3PMSF — the real test
The three-peak mountain snowflake — a snowflake inside a triangle outline — is a performance certification. To carry it, a tire must pass a standardized test: accelerate from 16 to 24 km/h on medium-packed snow. The tire has to outperform a baseline reference snow tire by at least 10%.
3PMSF means the tire has been tested and proven in severe-snow service. It's not a perfect rating — it doesn't test ice, deep snow, or cold-temperature handling — but it's the meaningful winter certification today.
Which tires carry 3PMSF?
- All dedicated winter tires (e.g. Blizzak, Hakkapeliitta, Winter Sottozero)
- Most all-weather tires (Michelin CrossClimate2, Nokian WRG4)
- Some all-terrain truck tires (BFG KO2, Falken Wildpeak A/T3W)
- Some all-season tires marketed for winter capability
What 3PMSF does NOT mean
- It doesn't mean ice traction — that's a separate test and rating not required for 3PMSF
- It doesn't mean the tire is a true winter tire compound — many all-weather and all-terrain tires carry 3PMSF without being optimized for sustained cold
- It doesn't replace the legal requirement for chains in some mountain passes
Should you require 3PMSF?
In many Canadian provinces (Quebec, BC) and several U.S. mountain regions, winter tires are legally required and 3PMSF or studded tires are the only ones that count. Even where it's not legally required, if you're shopping for any tire that might see snow service, 3PMSF should be on your checklist.
M+S is a tread pattern. 3PMSF is a test result.