Edmunds.com Asks, "Who Needs Winter Tires?"

Choosing the Right Equipment for Cold-Weather Driving


  • 2009 BFGoodrich Winter Slalom KSI Siping Picture

    2009 BFGoodrich Winter Slalom KSI Siping Picture

    Siping gives a tire more edges with which to grip ice and snow. | October 18, 2010

If you've never bought a set of winter tires, you're not alone. For many of us, it's how we were raised. If you grew up walking to school in the bitter cold, you weren't easily intimidated by Old Man Winter.

But be honest now: Fond as those memories might be, you did get stuck a lot, didn't you? And maybe crumpled some sheet metal, too? More than likely, it was because you lost traction on tires that weren't made to grip icy or snow-covered roads.

Tire technology has changed dramatically over the past generation. Indeed, it was 17 years ago when Bridgestone introduced its Blizzak model — the first of the studless winter tires to perform on par with studded tires — in the U.S.

These days, battling the elements is easier than ever. There are dozens of choices: multiple winter offerings from a number of tiremakers. On the other hand, in the era of antilock brakes, stability control systems, all-wheel-drive and all-season tires, who needs snow tires?

Evolution and Intelligent Design
Snow is just one challenge among many, so forget the term "snow tires." A more accurate term is "winter tires," as they're designed to improve acceleration, braking and handling across the whole range of cold-weather conditions.

Of course, such challenges have been overcome to some extent by the sophisticated safety equipment that's now standard on so many vehicles. It's easy to be lulled into a sense of near-invincibility by ABS, VSC and a slew of other engineering wonders whose three-letter-acronyms (TLAs) have become part of our everyday language.

But this technology is ultimately dependent upon the physics that takes place at four fist-size contact patches — literally, where the rubber meets the road. Vigilance upstream can only do so much to make up for bad behavior here. (AWD, by the way, will help you accelerate in the snow, but do little for your stopping and steering. And on ice, it's really all about the tires.)

The engineering involved in developing winter tires is, as one might guess, remarkably complex. Still, it more or less comes down to three factors: tread design, tread depth and the rubber compound.

The Nuts and Bolts of Tire Technology
Winter tires use siping, a series of slits in the tread blocks, to increase the number of edges in the tire's contact patch. As the tread blocks flex, each edge bites into the snow and ice. Greater tread depth allows for flexing and helps channel snow and slush across the tire's surface, away from the contact patch.

The type of rubber itself is also important. Winter tires are built using rubber compounds that remain soft even in extremely low temperatures. On the other hand, most summer and all-season tires use rubber compounds that harden at low temperatures, resulting in compromised cold-weather performance.

"The hardness of these tires at lower temperatures means they no longer conform to the surface of the road," says Joerg Burfien, director of research and development for Continental Tire. "This leads directly to reduced grip on the road and a much-reduced overall performance — mileage, braking distances, cornering, handling, etc. — ranging from 20-25 percent."

In an appeal to tire dealers, published earlier this year in Tire Review, Burfien warned: "Stopping distances can double if you are not using a winter tire as temperatures decline." Sounds like a man who wants to sell you another set of tires, doesn't it?

The thing is, he's right.

Last year, Inside Line compared different performance characteristics of summer, all-season and winter tires in various conditions, including — of course — snow and ice. The all-season rubber took 16-18 percent more real estate to stop, compared to the winter tires. And the summer tires? More than 120 percent longer.

Skid pad numbers illustrated a similar trend, but the differences in straight-line acceleration were truly remarkable. Whereas all-season tires slowed 0-40-mph times by 24 percent, their warm-weather cousins took 257 percent more time — nearly 42 seconds — to propel our Civic Si sedan across the frozen tundra.

The lesson? For winter driving, you need winter tires.

Seasons Change. Why Not Attitudes?
And still, Americans have been slow to take advantage of this cold-weather technology. "In 2008," writes Denise Koeth, managing editor of Tire Review, "the winter tire market made up 2.3 percent of the U.S. tire market, with 5 million units sold, and 34 percent of the Canadian tire market, with 8.3 million units sold." (Comparable numbers aren't available for 2009.)

No doubt one contributing factor is the ubiquitous all-season tire, and the promise embedded in its name. "The problem with the all-season tires," says Ron Margadonna, senior technical marketing manager for winter tires at Michelin North America, "is that people have a higher expectation on the delivery of the winter component, particularly when they live in an area where they really need a winter tire. I think that's a fundamental problem."

Of course, winter tires can be a hard sell in parts of the country where precipitation is generally limited to the liquid variety. But, with today's improved cold-weather offerings, many drivers south of the Snowbelt ought to be rethinking their choice of tires, too.

According to Burfien, these tires are not just for snow and ice; their softer compound also allows them to perform better on dry roads when temperatures dip below 45 degrees Fahrenheit. "Because they don't become stiff and brittle as all-season treads might," he says, "winter tires deliver more consistent and reliable grip as temperatures drop."

Picking the Right Cold-Weather Tire
OK, OK. But which winter tire? The variety, many of which have names straight out of a Pixar blockbuster — in addition to the aforementioned Blizzak, there's Dunlop's Graspic, Hankook's Icebear and Nokian's Hakkapeliitta — can be overwhelming.

Generally speaking, winter tires come in two flavors — categorized by the folks at Tire Rack as "Snow & Ice" and "Performance." Tire Rack describes Performance tires as "low profile, H- or V-speed rated tires...designed to suit winter driving on European highways." Which may also be code for "U.S. drivers in denial."

For drivers committed to navigating truly apocalyptic weather, on the other hand, the choice is pretty clear — assuming studded tires aren't permitted where you live. "If you want the best tire when conditions are the worst," says Woody Rogers, product information specialist at Tire Rack, "it's a studless snow and ice tire."

Winning Hearts and Minds
For some consumers, especially those who aren't sold on winter tires to begin with, the semiannual ritual of swapping tires has been a convenient excuse to stick with something — anything — year-round. The solution? A dedicated cold-weather wheel-tire set.

Among the many advantages is the wear and tear you save on your wheels. Each time you have tires removed or installed, you run the risk of damaging those pricey alloys — some of which cost nearly as much as a set of winter rubber mounted on steel rims (assuming a steel option is available). Tire-pressure monitoring system (TPMS) sensors are also vulnerable (see note below).

Of course, having two sets of tires also extends the life of your fair-weather rubber. And again, if you're running something fancy, the savings can go a long way toward the purchase of winter gear.

A standby set also allows you to prepare for the inevitable on your own terms. Rather than waiting until the snow flies — and then competing for an appointment with fellow procrastinators — you have the option of doing it yourself, in your driveway or garage.

Going Small
If all that weren't enough, there's another — less obvious — benefit: minus-sizing, something Rogers says tire dealers have promoted for years. It's "the reverse of plus-sizing," he explains, "which people often do in the summertime to gain performance and handling on clear roads.

"With plus sizing, you typically go wider on the tire and lower on the aspect ratio, often with a larger-diameter wheel to improve the handling and performance of your car. Minus-sizing will take a standard fitment on the car and make the tire narrower, putting it on a smaller wheel so you get a taller aspect ratio. The basic size of the tire and how much air it holds remains fairly constant — you're just changing the shape of that envelope."

As a result, your vehicle goes through the snow, rather than over it. And with a narrower tire, there's less of it to go through. Of course, the drivers who benefit most from minus-sizing are those who live in the harshest climates.

Margadonna suggests another option along the same lines: dropping down a step in speed rating if it means getting a more capable winter tire, especially on ice (though, of course, this doesn't require a separate set of tires and wheels).

Drivers of TPMS-equipped vehicles need to exercise a bit of extra care when swapping wheel-tire sets. Or maybe not. Some systems "learn" on their own, while others can be programmed by any shade-tree mechanic in possession of the right tool. Still others require a trip to the dealer.

Whatever the case, TPMS is no excuse for running the wrong tires.

Speaking of excuses, don't even think about installing just two winter tires. Maybe your father used snow tires only for the rear axle of the family station wagon, but he also gapped the points on the distributor and added STP at regular intervals. Times change.

The Takeway
If you live in an area that gets consistently cold temperatures during the winter, a set of dedicated winter tires will make a world of difference. Contrary to popular belief, it's not the tread that makes all the difference, it's the rubber. Even if your daily driver has all-wheel drive, traction control and a really great set of all-season tires, it might not go anywhere if cold temperatures turn your tires into rocks.

Winter tires not only have more aggressive tread designs, they also have rubber that stays soft in the coldest temperatures. It's a difference that you'll feel no matter what kind of vehicle you drive. Sure, swapping out tires twice a year is a bit of a hassle, but you'll get better performance and longer life out of each set of tires.

"It's like any other specialized piece of equipment you have for a hobby, or for your work," says Rogers. "Once you have the right tool for the job, you'll never use a hammer for a pair of pliers again."

Ready to put away your hammer? Then check out Inside Line's Winter Tire Buyer's Guide, where you'll find 25 different winter tire options from 14 manufacturers, representing the whole range of tire technology and vehicle fitments.

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