Winter tires are smart thinking

Don’t call them snow tires. If you live where fall colors give way to snow and ice-covered roads, buying a set of winter tires may be a prudent decision.  

We recently put Michelin’s latest and greatest X-Ice Xi3 winter rubber to the test in a controlled setting—the hockey rink at the University of Notre Dame, not far from retailer Tire Rack’s corporate headquarters. Although we never got above 15 mph, we were reminded of how effective dedicated winter tires are on a slippery, cold surface.

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Think of tires as you would your shoes. If it’s a snowy day, would you put on a pair of slick-bottomed dress shoes or high heels? Not unless you wanted to end up doing snow angels at the bottom of your driveway.

Need quantifiable evidence? In Quebec, winter tires were made mandatory about a decade ago. In just a few years, the Quebec Ministry of Transport found a 17 percent drop in winter crashes and a hefty 36 percent decline in deaths or serious injuries attributable to snowy weather car crashes.

Few places in North America aside from some mountain passes in the Western U.S. and some parts of Canada have made winter tires mandatory, but laws here are beginning to catch up with those in most of northern Europe where they're required. That doesn’t necessarily mean that you need to wait for legislation.

What makes winter tires different?

Winter tires have largely supplanted dedicated snow tires for most manufacturers. The difference here is that winter rubber consists not only of tread designed to bite into snow and ice, but also a specific rubber compound that’s vastly different from the all-season or summer tires your car was delivered with.

Obvious at first glance is the siping integrated into the tire’s tread. Sure, it’s possible to have a tire shop cut sipes—thin lines—into non-winter tread blocks, but that’s kind of like trying to shove a dress shoe into a hunting wader. It works, but not really.

Siping is designed to both wick away moisture and to adhere to a slippery surface. Newer siping technology employed by several big tire manufacturers helps the tires last longer while improving grip.

What’s not as noticeable is the rubber compound itself, which takes advantage of silica-infusion technology to make for a far stickier surface on cold surfaces both dry and frozen. Summer tires—the kinds you’ll find on most sports cars—are exceptionally ill-suited to cold roads for the same reason that they stick like glue on a warm day. The rubber compound used on summer tires becomes rock-hard and smooth as glass below about 45 degrees, making sports cars downright dangerous—if not entirely undriveable. All-season tires are better, but Tire Rack’s Woody Rogers calls them a “jack of all trades and master of none,” noting that they’re perfectly fine for quiet three-season highway cruising but come up short as temperatures drop due to both the rubber employed and especially to their tread.

But I have all-wheel drive, you say

Just because a Ford Explorer dashing through the snow on a winter’s day makes for great advertising doesn’t mean it isn’t without its limitations.

Like passenger cars, SUVs and crossovers come standard with all-season tires that run out of grip—literally—when the thermometer plummets. That means that they’re only marginally better at accelerating on a slippery road and, if anything, they’re actually worse at braking, says Tom Carter, a 30-year veteran of Michelin’s technical department.

“Every vehicle relies on four tires to turn, go, and stop,” Carter said. “A four-wheel-drive vehicle just means there’s more mass to bring to a stop.”

Generally, four-wheel-drive versions of crossovers, SUVs, and cars weigh a few hundred pounds more than their two-wheel drive siblings.

That’s not to say that four-wheel drive isn’t worth the extra cost, which typically runs around $2,000 on a mid-size crossover. On Notre Dame’s slippery ice rink, we tried to accelerate from a complete stop to 70 feet in two all-wheel drive Kia Sportage crossovers and then applied the brakes hard to see how they’d fare. One was fitted with original equipment all-season tires and the other in a set of new Michelins.

The difference was staggering. In just 70 feet, the winter tire-fitted Sportage clawed into the surface and accelerated consistently to about 18 mph. The Sportage with all-season rubber, meanwhile, struggled to hit 12 mph. The two braked in about the same distance, but it’s worth remembering that the winter tire Sportage was traveling about 75 percent faster.

The practicalities

Running winter tires does force some compromises, however. Ignore the fact that they require an up-front purchase since they’ll extend the life of your other tires. Focus instead on the cost of mounting and balancing two sets of tires twice a year, which runs around $80 in most shops.

However, Tire Rack’s Rogers suggests looking at a separate set of wheels and tires in a smaller diameter for many cars. Opting for a smaller wheel and tire setup means you’ll end up with a taller tire sidewall, which improves ride quality and often costs less.

“Tires 19-inches and larger are expensive to replace, so it may be cheaper for you to run 18-inch wheels with winter tires than simply buying a new set of 19-inch summer or all-season tires,” Rogers said.

There’s also the issue of storage, although Rogers reminded us that a stack of storage is “about the size of the stack of boxes full of stuff in my basement from before I was married.”

Maybe it’s time to clear out that box of memories you’ve forgotten. Your off-season tires would look great there.