Choosing winter tires: what works best when the Rubber Meets the snow? (Family Camping Guide).
So the first step in choosing the right winter tire is assessing where you're going to be doing most of your driving, and then matching those road or trail conditions to the various tire types available. You may be able to use your mud- or rockcrawling tires with very few modifications. Or you may need a dedicated winter tire. Let's see if we can help point you in the right direction.
They used to be called "snow tires," but over the past couple of years that name has been dropped by most tire manufacturers in favor of the "winter tire" designation, since dedicated winter tires are designed to handle more than just snow. These are the tires that most truck and SUV owners will switch to during the winter months, as they offer improved traction over the mix of road surfaces that people typically encounter in the winter, including snow-packed and icy roads.
The most hard-core of this bunch are the "severe snow condition" tires. According to the Rubber Manufacturers Association (RMA), these tires feature "tread patterns, construction elements, and materials that provide superior snow performance" over other types of tires, even those the RMA used to classify as snow tires. The RMA has developed a severe snow tire icon--a graphic of a snowflake on a mountain--that appears on the tire's sidewall near the more traditional M+S (mud and snow) designation. The tires that carry that icon have scored a traction index of 110 or higher while undergoing the American Society for Testing and Materials traction tests on packed snow.
Bill VandeWater, the consumer products manager in sales-engineering for Bridgestone/Firestone, told us there are two major components that make for a good winter tire: tread compound and biting edges. A dedicated winter tire will have a tread compound that is designed to stay pliable even when the weather dips below freezing. A flexible tread will grip the road surface--be it snow, ice or wet pavement--better than one that is rock hard.
"Our Bridgestone Mud Dueler, for example, is designed with a tread compound that will grip in temperatures of 40 or 50 degrees [Fahrenheit] and above," he explained, "but in cold weather that compound gets so hard that it just bridges over road surface irregularities and doesn't grip." Bridgestone's Winter Dueler, which has earned the RMA's severe snow rating, is made with a tread compound that will remain flexible at temperatures down to 0 degrees F, so it will be able to grab and grip whatever the road surface offers.
The second component--biting edges--typically come in the form of small, razor-like sipes, or cuts, in the winter tire's tread pattern. VandeWater said, "All these sipes present biting edges that grab into the snow. The Winter Dueler is heavily siped. The Mud Dueler isn't, as all those sipes would tear on rocks and be counter to the longevity of the tire."
Speaking of longevity, VandeWater admitted that a winter tire's soft compound and heavy siping contribute to a tread that would wear more quickly than a non-winter tire if used on pavement when the weather gets warm. It would probably provide excellent grip, but only for a few thousand miles. If the Winter Duelers are used only during winter-weather conditions, which means over a typical mix of snow-covered and bare pavement roads during cold-weather months, they should be good for at least three to four winters," VandeWater estimated, "maybe five or six if they're used only in the snow."
Other truck and SUV tires that have earned the RMA's severe snow rating include the BFGoodrich All-Terrain [T/A.sup.KO], the Goodyear Wrangler Ultra Grip Ice, and the Michelin 4x4 Alpin.
Off-Road Tires in the Snow
Except for the BFG All-Terrain mentioned above, most of the tire manufacturers we spoke to were hesitant about recommending a "typical" all-terrain or max-traction tire for winter use, since most of these tires don't feature a soft compound or heavily siped tread pattern engineered specifically for cold-weather traction. Yet they agreed that, under certain conditions, a maximum-traction tire would perform better than a so-called winter tire.
Those Conditions: Virgin Snow
If you do a lot of trail busting, or driving over snow that hasn't been packed down by other vehicles or plows, you're going to find that your mud tires will work great. That's because this kind of snow condition is a lot like driving in the mud. Your tires are going to need to claw for all the traction they can get, while not getting packed up with snow caught between the tread blocks. Plus, depending on the snow's depth, you may find that your tires will claw down through the pack and hit rock, stumps, or logs, and you're going to need your mud tire's cleats to track over those obstacles.
Speaking of digging down, there's a fair amount of disagreement over whether digging or floating is the best way to get traction in the snow. Some say you need to dig, with fairly narrow tires inflated to recommended street pressures, in order to find grip on the ground below the snow. Others take an approach more like running in the sand, and air down their tires so they'll act like snowshoes and float over the drifts. Like everything else, your approach will depend on a lot of factors. Are you driving a fullsize pickup or SUV that's too heavy to float? Are you traveling over snow that's so deep there's no ground to reach? As we've said before, tailor your approach to the conditions you're in.
Know, too, that the tire manufacturers take a dim view of underinflating tires, under any conditions, and will warn against the practice because of potential damage to the tire. But we've seen 'wheelers, here and in Iceland, who have great success floating over snowpack and even glaciers with their mud tires aired down to single-digit psi levels.
Whichever approach you take, make sure you go into the winter months armed with four good-quality tires that have plenty of tread left on them. If you're going to use dedicated winter tires, especially those with the severe snow condition rating, make sure all four corners have the same type of tire, so one end of your rig doesn't get a lot more traction than the other, which could make handling a nightmare. And don't get overconfident in your truck's traction abilities just because it's a 4x4. Your truck still contacts the ground through its tires' contact patches, not the transfer case and axles.
RELATED ARTICLE: Winter Weather Tire Tips
Whether you're using dedicated snow tires or your mud tires, winter cold will have an effect on them that you may not expect. For example:
* If you get stuck in a snowdrift, don't just spin your tires. Not only will you dig in further, but the centrifugal force of the spinning tires may cause them to explode. Rock back and forth, shifting between First and Reverse, to free your tires. Make sure your speedo never exceeds 35 mph if you're trying to spin and rock your way out of a drift.
* Expect the air pressure in the tires to drop 1 to 2 psi for every 10-degree drop in ambient temperature. Keep a tire pressure gauge handy (if you don't already) and check pressures often.
For absolute maximum traction in the snow, many drivers like adding studs to their snow tires. But studded tires are outlawed in some states, while others have restricted their use to certain months. For a state-by-state list of studded tire regulations, visit this link on the RMA Web site: www.rma.org/tiresafety/seasonal_tires.html.
Or check with your local DMV.
Winter Driving School
If you find yourself spinning your wheels more often than not in the snow, you may need some lessons in vehicle control. Bridgestone operates a Winter Driving School near Steamboat Springs, Colorado, that offers everything from half-day safety lessons to two-day high-performance driving programs. There's even a class for competitive rally drivers. Lessons are taught in the class room and on a mile-long, 10-turn, ice-covered racetrack with snow-covered guardrails that "pardon" driver errors. The vehicles used in the school include FWD cars, fullsize pickup trucks, and 4x4 SUVs.
The lessons range from $155 for a half-day Winter Safety Program to $1,550 for the two-day Performance Program or Rally Race School. For more information, call 800/WHY-SKID (949-7543) or log on to www.winterdrive.com.
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|Date:||Dec 1, 2002|
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