The Margin of Safety
Winter Tires are designed to deliver safety and control in snow, ice, and cold weather conditions. Many people think that all-season tires can deliver this same performance, but this is not true. The superior traction that winter tires deliver, as much as a 25 to 50 percent increase over all-season tires, can very well be the margin you need to stop in time or turn to avoid trouble. The Rubber Manufacturers Association (RMA) has set a new standard for winter traction that is explained in detail after the video.
Winter tires have special tread compounds that use one or more of the following features to deliver improved traction:
- "Soft stud" tread fibers that "bite" like metal studs yet are quiet and do not harm the road
- Special compounds that retain their flexibility even in the coldest temperatures (A more flexible tread surface equals more traction and control.)
- Silica-based, micro pore compounds (or comparable technology) that are used to bite through the water film to increase snow and ice traction
Meanwhile, all-season tires use very different compounds. These compounds are "averaged" to deliver better wear and good traction in a wide variety of conditions. However, the trade-off is a decrease in traction in conditions below 45 degrees Fahrenheit. This is the point where all-season tire compounds begin to harden and lose traction. These tires must use denser compounds in order to deliver better wear. Micro pore or comparable technology is not suitable for these designs. For the same reason, no soft stud material is built into these tires.
Winter tires have tread designs dedicated to improving snow and ice traction. Today's most advanced winter designs deliver this while maintaining a comfortable, quiet highway ride as well as excellent dry traction. Winter tires use the following features in their tread design:
- Wider circumferential grooves that enhance winter traction by providing efficient channels to drain water and expel snow
- Smaller shoulder grooves that increase snow and ice traction with no sacrifice in dry handling or highway ride
- Sophisticated, high-density sipe designs that help cut through water and slush so the tread compound can make better contact with the road
- Rounder casing designs that add traction by cutting into the snow's surface
All-season tires can not include these features and still deliver the wear and high temperature traction that is required for driving during other times of the year. The following details also make all-season tires less desirable for driving in winter conditions:
- Shoulder blocks and groove designs that are "compromised" to meet cornering, wear, and all-season traction requirements
- Less aggressive tread design that delivers more highway ride comfort but fails to expel snow as efficiently as winter tires
- Less siping than winter tires
- Flatter tread designs that enhance dry traction but don't cut into snow effectively
The Stamp of Approval
To help you select a winter tire that improves your margin of safety, the
RMA designates winter tires that meet the new severe snow standard with a new
symbol. This sets them apart from standard M&S (mud and snow) rated all-season designs.
Remember that four winter tires are recommended to achieve optimum traction and safety.