Despite the name, all-season tires are not appropriate for
winter weather. In delivering a comfortable experience in a wide range of
temperatures, all-season tires are far too compromised for adequate winter
performance. Even with mud and snow ratings, all-seasons don’t compare in grip
and performance to real winter tires which feature the mountain and snowflake
symbol on their sidewalls.
“In earlier years when a tire had the M+S symbol on the side
we would say it was fit for use in mud and snow,” Rene Wolters of Vredestein
Tyres said. “Most all-season tires have this M+S marking on the side, but do
not nearly perform as a winter tire should.”
Winter tires are specifically made to handle snow and ice.
For example, thanks to special construction of the rubber compound, snow
doesn’t stick in the grooves of a winter tire.
“A true winter tire performs much better than that and can
be recognized by a symbol on its side depicting a little mountain top with a
snowflake. Only tires with this symbol are suitable for use in true winter
conditions,” Wolters said before emphasizing that “most All-season tires do not
have this marking and are not fit for adequate use in the winter.”
He points out that the materials that make a tire stickier
at low temperatures make them less grippy at higher temperatures. That means
that winter tires are specially made for snowy seasons, while all-seasons are
not made for any season in particular.
“Another important element in winter tires is siping,”
Bridgestone product manager Kurt Berger said. Sipes are grooves that are cut
into a tire’s tread block. “Siping is a major contributor to a winter-tire’s
performance. It allows the tire to gain additional ‘biting edges’ for better
grip.”
Depending on its placement, siping can affect noise,
traction, water-removal and overall driving feel. A tire with straight, wide
grooves will tend to have good anti-hydroplaning characteristics and should be
less noisy than other tires. A tire with more lateral grooves will have more
traction. However, too much siping and the tire can feel less stable and is
likely to wriggle around on dry roads. Zig-zag siping patterns are another
approach. Some of Bridgestone’s tires, for example, use that pattern, something
Berger said enhances grip while corners.
Different types of Tires for Winter
Choosing the right winter tires isn’t easy. It helps to know
if you’ll be dealing with icier driving conditions, or more snow. While no
winter tire is designed specifically for ice, or snow, there are tires that
cater more to one situation. Tires that are more suited for ice are made of a
different chemical compound called silica which keeps the rubber flexible in
colder climates. This results in better performance on ice, and it’s also
likely that the tread on these tires will help keep noise down. Overall, tires
that are made for ice will be better for drivers who spend a lot of time on
freeways.
In contrast, snow biased winter tires have wider gaps
between tread blocks, and are a bit stiffer. This makes them better at
traversing up mounds of snow. “Snow grips to snow” explains Berger.
Some designs are shared between different types of winter
tires.
“We found that in winter driving, a thin film of water
lubricates the tire,” Berger explains, “So our ‘Multicell’ tread compound uses
microscopic pores to help get rid of that water.” This technology is great for
both snow and ice conditions.
Why take the chance?
Tires are the way a car interacts with the road. Even the
latest high-tech safety systems, from advanced all-wheel drive to stability
control, will be rendered useless if your car has no grip. When the road is all
icy, or covered with slippery snow, you need a tire that can deal with those situations.
Winter tires feature specially designed tread patterns that
provide more surface area to contact the road and provide superior grip.
Even cars with all-wheel drive should consider winter tires.
All-wheel drive systems might help with stability in slippery conditions, but
they won’t do much when you need to stop. Driving on a slope with no traction
on your wheels, even with an all-wheel drive system can still prove to be
dangerous. A set of winter tires provides the grip necessary to drive safely in
any situation involving snow and ice.
Plenty of studies have been conducted to see how important
winter tires are. A recent study conducted in Canada showed that no matter the
vehicle, winter tires greatly decrease braking distances over all-seasons. In
fact, one study showed when a car is travelling just 30 mph in winter
conditions, that winter tires can reduce your stopping distance by up to 25
percent, or between two to three car lengths.
Some drivers think that they can get away with just using
two winter tires, to be put on a cars driving wheels. This is a big mistake and
can be dangerous in the snow. “Using a different set of tires on front than the
rear can cause problems when cornering,” said Berger. He explained that when
two different sets of tires are used, one end of the vehicle will likely lose
traction during cornering situations.
A big concern about winter tires is when to put them on.
All-season tires lose effectiveness at around 45 degrees Fahrenheit, which is
about the same time you can see your breath. As soon as you start noticing your
breath in the wind, it’s time to switch tires.
Source: Sami Haj-Assaad, Autoguide.com
