While it's obvious that winter tires can make an automobile easier and safer to drive in inclement weather, it can be trying to figure out which tire to buy and when to put it on can be confusing. Getting optimum winter performance from your vehicle also requires a little know-how about storage, wheel options, legalese and pictograms.
Most traditional tires are "all season," balancing dry pavement grip with wet weather and mild winter performance. However, severe cold can make the tread compound brittle, reducing grip. The abbreviations "M&S" and "M+S" found on some of these tires stands for "mud and snow." This does not mean it is a winter tire: This label is determined only by the tread depth, not the tread compound or cold weather performance.
Performance and summer tires eschew rain and winter traction to provide the best performance on dry roads. Their soft tread compounds are even more susceptible to cold temperatures, and their shallow channels can't move snow away from the tire surface. Even in mild winter weather, performance tires can make a car all but immobile.
Winter tires have specially formulated tread compounds that can handle cold temperatures. The tread itself is very deep to displace snow, and has either studs or a micro-porous surface compound to get a grip on icy surfaces. Like summer tires, the tread compound is very soft, letting the tire deform around the road surface for better contact.
Performance winter tires are a recently added category. These trade some of the ice and snow performance of a regular winter tire for better dry surface traction. These are a good choice for those who occasionally need to drive through inclement weather, while compromising on-road performance as little as possible. These are the only type of winter tire offered in some low profile sizes.
Thanks to a labeling program instigated by Transport Canada (the Canadian equivalent of the Department of Transportation,) it's easy to identify which tires fall into this category. Any tire that has a sidewall marking of a mountain silhouette with a snowflake meets standards set forth by the U.S. Rubber Manufacturers Association (RMA) and the Rubber Association of Canada (RAC) for severe winter use. A vehicle that has these tires can legally be driven on roads in either country that require the use of traction devices. Nearly every winter or winter performance tire meets this standard.
Studded tires have dozens of tungsten carbide pins attached via metal jackets inserted into the tire tread. These pins can bite into ice, providing better traction on slick surfaces than any other tire on the market. However, dry
pavement performance is less than optimal: The flat, inflexible surface of the pins reduces traction and causes tremendous amounts of road noise. Tread support for the studs also requires compounds that lose their flexibility in extreme cold, further reducing road performance. The tire studs also cause rapid road wear; as a result, most states restrict their use to only a few months out of the year.
Studless tires use a soft traction compound with microscopic pores that both grip the road and wick away the thin film of water created when the warm tire meets the surface ice. On dry pavement, they are still able to maintain their grip regardless of temperature, making them a good all-around choice for winter driving.
For most drivers, studless tires are the best option. However, if the vehicle is only driven on ice or snow-covered roads, particularly unpaved roads, studded tires can offer better performance.
The soft tread compound used on these tires makes them wear more like a performance tire than an all-season or touring tire. Due to the widely varying driving conditions these tires face, it's hard to pin down an exact lifespan for winter tires. Three to four seasons seems to be the norm for most drivers.
Michelin became the first tire company to offer a tread wear warranty on a winter tire earlier this year, offering coverage for 40,000 miles on their X-Ice Xi2 and Latitude X-Ice Xi2A tires. Otherwise, manufacturer and installer warranties exclude coverage for winter tires.
Yes. 4WD and AWD systems help the vehicle get a grip on slick roads when accelerating by distributing power output to every wheel, but this has no effect on braking. The benefits don't end there: Even if the vehicle is outfitted with the most advanced traction control system on the market, it can only dole out power within the limits of tire traction. Switching to winter tires will improve driving performance, whether braking, turning or climbing a steep hill.
Yes. Again, as with four wheel drive vehicles, tire grip is the limiting factor. While using winter tires on the front of the car improves traction for acceleration, the difference in grip between the front and rear of the car can cause severe understeer. Even at low speeds, the car spin out. Although most braking is done at the front of the car, using a set of four tires instead of a mix of winter and all-season rubber can decrease stopping distances by as much as 25%.
Using winter tires only on the drive wheels of a rear wheel drive vehicle can be even worse: Without proper grip, the front wheels have little effect on steering, putting the car into a skid when making turns. Braking performance is also drastically effected.
No. Manufacturer tire pressure recommendations will provide optimum tread contact. Underinflating a tire can make the contact patch uneven while providing too little sidewall support, hurting performance. Keep in mind that tire pressure fluctuates depending on tire pressure: Tires will lose 1 psi of pressure when the temperature goes down by 10 degrees Fahrenheit (5-6 degrees Celsius.) This can represent as much as a 6 psi difference between high and low temperatures during a normal winter.
Winter tires perform best at temperatures below 35 degrees Fahrenheit (2 degrees Celsius.) The general rule of thumb is to use winter tires when the average temperature is below 50 degrees Fahrenheit (10 degrees Celsius) or lower. For most northern states, this means running winter tires from late October to early April, although this could extend to half the year or more for extreme climates.
"Safe" is a relative term. The tire's tall, soft tread blocks will cause the vehicle to squirm at high speeds, and the tread compound will wear much faster in higher temperatures. While its OK to move a clunker around once or twice with winter tires installed, using them on a daily driver is not advisable.
The tires should be stacked on top of one another, with up to four tires per stack. They should be kept in a cool, dry place like a garage or basement. Storage bags will keep the tire surface from cracking due to ozone exposure: This is particularly important near furnaces, as the heat can generate large amounts of this gas.
While there's nothing wrong with switching between regular and winter tires, having a set of winter-only rims can pay for themselves over time by reducing mounting and balancing costs. Most owners who go this route choose to have steel wheels installed because they're cheaper than alloys and because they don't have a finish that can show ice and salt damage.
For vehicles that have plus-sized wheels, either as original equipment or as an aftermarket installation, it may be possible to fit a smaller wheel together with a taller tire. Many drivers choose to go this route because it can open up a wider range of snow tire options. Normally, if the vehicle comes with a smaller wheel from the factory using the same brake package, it will fit. This isn't an option for most sports cars as they need large wheels with low profile tires to both accommodate their brakes while still leaving enough space between the outside of the tire and the fender. When in doubt, consult a professional installer.
Regardless of your tire and wheel choice, overall diameter of the wheels and tires should be the same as the original equipment for the vehicle.