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The Margin of Safety |
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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 below. |
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Tread Compound |
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Winter tires have special tread compounds that use one or more of the following
features to deliver improved traction: |
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1. “Soft stud” tread fibers that “bite”
like metal studs, yet are quiet and do not harm the road |
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2. Special compounds that retain their flexibility even in the
coldest temperatures (A more flexible tread surface equals more traction and
control.) |
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3. Silica-based, micro pore compounds (or comparable technology) that
are used to bite through the water film to increase snow and ice traction |
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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. |
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Tread Design |
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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: |
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1. Wider circumferential grooves that enhance winter traction by providing
efficient channels to drain water and expel snow |
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2. Smaller shoulder grooves that increase snow and ice traction with no
sacrifice in dry handling or highway ride |
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3. Special lug and groove shapes allow more snow to be packed into the tread and
expelled as the tire rotates for better deep snow traction. |
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4. Sophisticated, high-density sipe designs (sipes are the little slits in the tread
surface) help cut through water and slush so the tread compound can make better contact with the road |
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5. Rounder casing designs add traction by cutting into the snow’s surface |
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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: |
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1. Shoulder blocks and groove designs that are "compromised" to meet cornering,
wear, and all-season traction requirements |
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2. Less aggressive tread design that
delivers more highway ride comfort but fails to expel snow as efficiently as
winter tires |
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3. Less siping than winter tires |
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4. Flatter tread designs that enhance dry traction but don't cut into snow
effectively |
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The Stamp of Approval |
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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. |
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Remember that four winter tires are recommended to achieve optimum traction and
safety. |
