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by: Mat Johnson    

 

It's obvious that winter tires make an automobile easier and safer to drive in harsh winter climates. It also can be a confusing and difficult decision, when deciding which winter tires to buy for your vehicle. Getting optimum winter performance from your vehicle is important and also requires a little knowledge as to which tires best fit your vehicle.

What makes a winter tire different from any other tire?

The traditional "all season" tire balances dry pavement grip with wet and mild winter performance. However, severe cold can make the rubber compound on the tread brittle and reduce grip. The "M&S" and "M+S" found on some tires stands for "mud and snow". This doesn't mean it is a winter tire. This label only determines the tread depth not the tread compound or cold weather performance.

Summer and performance tires refrain from rain and winter traction to provide the best performance on dry roads. Their soft tread compounds aren't engineered to handle the cold temperatures, and the tread design isn't built to channel snow out like winter tires do. Even in mild winter weather, performance tires can make a car all but immobile.

Winter tires have specially engineered tread compounds that can handle cold temperatures. The tread is designed with more sipes, deeper tread to displace snow, and either studs or a micro-porous surface compound for better grip on icy surfaces. Like summer tires, the rubber compound is very soft and flexible, letting the tire deform around the road surface for better traction.

Performance winter tires are a recently added category. These offer the performance of a performance tire into a snow tire. These are a good choice for those who occasionally need to drive through canyon type road conditions. These are the only type of winter tires offered in some low profile sizes.

Are winter tires considered "traction devices?"

Thanks to the labeling program instigated by Transport Canada (the Canadian equivalent of the Department of Transportation,) it makes it simple to identify which tires fall into this category. All tires that have a sidewall logo of a mountain silhouette with a snowflake meet standards set forth by the U.S. Rubber Manufacturers Association (RMA) and the Rubber Association of Canada (RAC) for severe winter use. A vehicle equipped with these tires can legally be driven on roads in either country that enforce this law. Mostly every winter or winter performance tire meets this standard.

Which is better: Studded or Studless tires?

Studded tires are built with dozens of metal tungsten carbide pins that are inserted into the tire tread. These pins bite into the ice, providing better traction on slick surfaces than any other tire on the market. However, dry pavement performance differs. 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. As a result, most states restrict their use to only a few months out of the year, due to the fact that studs cause rapid road wear.

Studless tires use a soft traction compound with microscopic pores that both grip the road and wick away the thin film of water when the tire meets the icy surface. Even 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, it depends on where the vehicle is going to be driven. For ice or snow-covered roads, or unpaved roads, studded tires offer better performance.

How long does a winter tire last?

The soft rubber compound used on winter tires can make them wear more like a performance tire than an all-season or touring tire. Due to widely varying driving conditions, determining the lifespan of a winter tire can be difficult. 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, 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.

Is there any reason to get winter tires on a vehicle equipped with four wheel drive or all wheel drive?

4WD and AWD systems do help the vehicle get a grip on slick roads when accelerating, but this has no effect on braking. 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.

Are four winter tires really needed on a two wheel drive car?

Once again, Yes. Like four wheel drive vehicles, tire grip is the limiting factor. While using winter tires on the front of the car improves traction for acceleration, having better traction in the front than the rear can cause severe under-steering when turning. Even at low speeds, the car can 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 rear 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 affected.

Will running a lower tire pressure improve grip?

No, it won’t. Setting tire pressure at manufacturer spec provides optimum tread contact for your tires. Underinflating a tire can make the contact patch uneven while hurting performance and providing very little sidewall support. Keep in mind that tire pressure fluctuates depending on the weather. 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.

When should winter tires be installed?

Winter tires perform best at temperatures below 35 degrees Fahrenheit (2 degrees Celsius). The basic time to install winter tires is when temperatures reach below 50 degrees Fahrenheit or 10 degrees Celsius and lower. So for most northern states, it is wise to run winter tires from late October to early April.

Are winter tires safe to use during the summer?

"Safe" is a relative term. The tire's tall, soft tread blocks will cause the vehicle to squirm at high speeds, and cause the rubber compound to wear much faster in higher temperatures. While it’s OK to move a clunker around once or twice with winter tires installed, using them on a daily driver is not advisable.

How should winter tires be stored?

When storing winter tires, they should be stacked one on top of another with up to four tires per stack. They should be stored in a cool, dry place like a garage or basement. Keeping them in storage bags will prevent the tire surface from cracking due to ozone exposure. It is also important not to store them in places near furnaces, as the heat can generate large amounts of this gas.

Should winter tires be mounted on their own rims?

While there's nothing wrong with switching between regular and winter tires, having separate sets of winter and summer wheels 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 of the cheap cost and the fact that they don't have a finish that can show ice and salt damage.

Vehicles with plus-sized wheels, either as original equipment or as an aftermarket installation, may install a smaller wheel together with a taller tire. Many drivers choose to go this route, because it opens a wider range of snow tire options. 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.

Winter Tire Decision Guide - Tire Central and Service was written by Mat Johnson of Tire Central and Service