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. 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 people enforcing the regulation can be confused by tire jargon. 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.
Tire manufacturers and tire retailers use general classifications to categorize tire types. Terms like “all-season tires,” “all-weather tires,” “winter tires,” “summer tires” and “rain tires” are examples of tire classifications. While tire manufacturers group their tire styles per actual performance attributes, the groupings are quite arbitrary. One tire manufacturer may design a tire that is optimized for wet and dry conditions and call it a summer tire. Another manufacturer could have a product with the exact same performance characteristics, and market it as an “all-season” tire. 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. For this reason, law enforcement officers at roadside winter tire checks rely on additional information to differentiate tires intended for us on winter roads.
Tire Certifications and Markings
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. There are two common tire marking used for winter: “M+S” marketing and the “Three Peak Mountain Snowflake” symbol. 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. For this reason, it is important to check before you buy new tires. You could be buying a tire that is marketed as an all season tire for year-round use, with very good snow and ice traction, but without the “M+S” stamped somewhere on the sidewall, your tire may be deemed unsafe for travel on certain roads.
The M+S marking was introduced in the 1970s to distinguish tires with extra mud and snow traction from tires with ribbed treads, common in the era. For a tire to have the “M+S” grading and stamp on the sidewall, it had to have a particular style of block tread pattern and more traction capabilities. By today’s tire performance standards, the standards for this classification is actually quite low, particularly for typical winter driving conditions like packed snow and ice. However, the “M+S” certification system has become the benchmark to help the average tire buyer and law enforcement determine if a tire meets even the basic level of snow traction.
Three Peak Mountain Snowflake
In the late 1990s, the RMA realized that updated standards were required to differentiate ture “winter tires” from standard “all-season” tires. The new testing parameters included more winter traction specific testing, including a snow spin test. Today, the Three Peak Mountain Snowflake on the side of a tire remains the best indicator that the tire has good levels of winter traction you would expect from a tire classified as a true “winter tire.” While there are a few non-winter tires, like all-terrain light truck tires, that pass the traction test and carry the Three Peak Mountain Snowflake symbol, the large majority of tires with this symbol are true winter tires, intended to be used only during the winter months.
Winter Tire Laws and Regulation in Your Area
What does this all mean for you? If you drive in an area with winter tire laws and travel regulations, you should first learn the local winter tire laws. Dedicated winter tires are always a good idea for maximum safety, but most winter travel restricted roads will allow travel without winter tires if you have chains, and your all-season tires are in good condition and are appropriately marked. Regulations pertaining to tires and winter travel can vary from area to area however, so it is best to research before setting out on a trip through a mountain pass or new route that is subject to heavy snowfall.
At the very least, you should check your all-season tires for the M+S symbol on the side of the tire. The marking can usually be found close to the bottom edge of the tire that attaches the wheel as shown on the left. A law enforcement officer at a roadside winter tire check is first going to look at the tread, and the name of the tire. If they don’t recognize it as a dedicated winter tire, the next thing they will look for is the Three Peak Mountain Snowflake or the M+S symbol. Many will also look at the condition of the tires. If the tread is too worn, you could be asked to turn back, or be required to pullover and install tire chains.