A tire manufacturer is not obliged to submit their tires for testing, nor do they have to include these markings on the side of their tires.

There are two common tire marking systems used for winter: “M+S” marking, and the “Three Peak Mountain Snowflake” symbol. Over the years, the Department of Transportation (DOT) and the Rubber Manufacturer’s Association (RMA) have implemented certified testing and tire marking systems to help differentiate tires. For this reason, law enforcement officers at roadside winter tire checks rely on additional information to differentiate tires intended for use on winter roads. There is no way to tell exactly how a tire will perform or how a tire manufacturer classified a particular model just by looking at the tread, sidewall or name of the tire style. Another manufacturer could have a product with the exact same performance characteristics, and market it as an “all-season tire”. One tire manufacturer may design a tire that is optimized for wet and dry conditions and call it a summer tire. While tire manufacturers group their tire styles per actual performance attributes the groupings are quite arbitrary. Terms like “all-season tires”, “all-weather tires”, “winter tires”, “summer tires” and “rain tires” are examples of tire classifications. Tire manufacturers and tire retailers use general classifications to categorize tire types. The following is an explanation of the different tire classifications, certifications and winter tire markings to ensure that you don’t get stuck at a roadside tire check this winter. To keep safe and legally compliant when driving in these areas it is important to know the different tire classifications and tire certifications to distinguish between all-season tires and true winter tires. The objective of these laws is to improve winter travel safety, and prevent travel on unsafe tires, but everyone, including the people enforcing the regulations can be confused by tire jargon.

New winter tire laws and winter travel restrictions are popping up in regions of the country prone to heavy snow fall and extreme winter weather.

What does m and s mean