If you live in the Snow Belt, you're probably familiar with this scene: A tall SUV with lots of ground clearance speeds by on a snow-packed highway. Miles later you spot the vehicle, spun out on the side of the road and getting pulled out by a wrecker.
What most don't realize is that the type of tires you're riding on have a lot to do with how secure you are on a slick road.
Driving out into the blizzard in your hulking SUV with nearly bald all-season tires is downright silly; it's like setting out in the snow in a down jacket and all the right thermal gear but forgetting to swap out the mocs for boots.
Ultimate grip is only as good as the contact patch that the tires have and the grip they can manage. "That connection with the ground is all you have to work with," said Mark Cox, director of the Bridgestone Winter Driving School, in Steamboat Springs, Colorado.
Quite simply, if you have a job or position that requires you drive on snowy or icy winter roads before they're properly cleared, you should get winter tires, according to Jennifer Stockburger, a tire test engineer at Consumer Reports. "You can't beat the added traction of a winter tire," she said.
"All season tires are good where you might get occasional snow," says John Nielsen, director of AAA's Auto Repair and Buying Network. But you should consider M+S (mud and snow) tires, at the minimum, if you live anywhere that might see even occasional winter conditions.
The five main types of tires today are summer, all-season, M+S, winter, and studded.
Not so nubby anymore
Not too long ago, winter tires were easy to spot from a distance, because of their very aggressive tread and rough edges. Today's winter tires still do have deeper, more open tread patterns that are better at digging in, but they achieve their performance as much from a different type of rubber as they do from the careful, subtle design of the tread pattern details.
"Winter tires are designed to stay pliable in cold temperatures," said Stockburger, "and the pliability is going to help on ice," said Stockburger, especially in the most slippery situations, when the sun comes out and it's just below freezing, melting just a thin top layer of packed snow or ice and creating a thin layer of water on top. "Rubber sticks to ice, so as long as you can get rid of the water in between you'll have some grip," Cox explained, saying that the best tires today use a compound with small pockets that trap water droplets and fling them outward.
M+S is a designation that's based on tread pattern, not compound—essentially the equivalent of old-style snow tires—so M+S tires might not fare as well on ice. Look for that "mountain and snowflake" symbol for assurance that the compound is softer, or the term "studless ice and snow" in referring to true winter tires.
"Winter tires have come so far. They really are a different breed from ten years ago," assessed Nielsen.
Studded tires, which typically employ 80 to 100 small embedded metal studs into the tire's tread pattern, to help it dig into hard-packed snow and ice, are less necessary than they used to be but remain an option for those in some snowy, mountainous areas—mainly portions of the Rocky Mountain states and the Northwest. Although these tires do provide a little extra traction in some types of icy conditions, they do measurable damage to the roadway surface and most drivers will be just as well off using winter tires and carrying chains for extreme situations.
Tradeoffs as the weather changes
Once you get winter tires installed, you might notice a difference on dry pavement. Especially if the weather's warmer, the best winter tires are going to be a little "squishier and more compliant" on dry pavement, said Cox, with a slight drop in ultimate dry-road cornering grip. A lot of people initially say the vehicle feels "a little loose," in corners, added Matt Edmonds, vice president of Tire Rack.
But as soon as you're on a slippery surface, you'll notice the positives, and safer, more predictable handling as you're sliding is one of them. "When you lose grip, winter tires give you some feedback, so there's a better chance of regaining grip," Cox said, adding that standard all-season radials, when they become snow-packed, will lose grip suddenly and it's much harder to regain control until the car stops skidding.
The same physical rules that cause winter rubber compounds to become overly soft in hot weather also make summer performance tires dangerous as the weather turns cold. If you plan to drive a vehicle that has low-profile performance tires -- especially stiffer, high-speed-rated ones -- in cold weather and on slippery roads, winter tires are a must. These types of tires might not only fail to dig into the snow, they're also not very effective in moving moisture out of the way. And even on firm, dry asphalt, summer performance tires don't grip as well at colder temperatures.
A relatively new segment of the market is that of performance winter tires. In sizes to fit performance cars, and carrying higher speed ratings, they "have a little more road feel in dry conditions" at winter temperatures, said Edmonds, but Consumer Reports has found that "some of the best winter tires are actually poor for dry braking," according to Stockburger.
Don't try to use those winter tires year-round, though, even if you're willing to live with the tradeoffs when the mercury rises. "They will wear out in no time once the weather warms up," said Nielsen.
To the notion of the overconfident SUV driver, using inadequate tires with four-wheel drive or all-wheel drive puts you in the dangerous position of being able to accelerate more confidently than other vehicles, without being able to brake or steer any better than them. All-wheel-drive versions are typically heavier as well, which might make a vehicle more difficult to control in a skid, all else the same.
Typically, rear-wheel drive vehicles are going to gain the most from a winter tire, in winter conditions, according to Cox, who says the common belief is that low-slung, rear-wheel-drive vehicles are dangerous on winter roads. "From experience, that's not the case. If you put a good winter tire on it, you can drive it year-round."
An investment that could pay off
It's more than that. Thinking about safety and economics, it might just save you from slick-road fender-benders, and the cost of a set of winter tires is less than a typical insurance deductible.
With no single tire that performs well enough year-round for places with harsh winters, it makes sense to own two sets of tires, seasonally rotating the set of winter rubber with all-season or summer treads.
There's no doubt winter tires are pricey. According to Consumer Reports, the average price of V-speed-rated tires -- one of the higher, more expensive ratings -- is $99 each, while the average price of winter tires is $101 each. Adding to the impact is that winter tires don't last as many miles as their all-season counterparts. Stockburger said that winter tires should last three or four winters, on average, or about 30,000 miles. Cox cautioned, by the time you reach half of the original tread depth, "Even a half-worn winter tire is no better than an all-season radial in the snow," though it would still retain an advantage on ice.
"We tend to think of winter tires as a two- to three-season investment," said Edmonds. "While your winter tires are on the car, your other set of tires is resting."
That, and you probably have some extra peace of mind.