When it comes to snow tires, 3PMSF stands for "3-peak mountain snowflake." This symbol appears on the sidewall of a tire that meets the U.S. Tire Manufacturers Association's requirements for winter performance. The American Society for Testing and Materials independently conducts this testing. The 3PMSF rating is the standard for snow tires, and you should look for it if you drive in cold, snowy, or icy conditions.