You want to find tires that are rated for snow and ice. 'All-season' tires won't do it. Make sure that any tires you buy carry the 'mountain and snowflake' symbol stamped on the sidewall. This means that the tires meet specific industry standards for winter driving.
Over the past two weeks, many Portlanders were wishing they had a set of good winter tires. Even drivers with four-wheel-drive or all-wheel-drive vehicles may find themselves slipping off the road if the vehicle's tires are not up to the challenge of ice and snow.
When the lines at the tire stores die down a little bit, many of us will go out to shop for a new set of winter tires, also known as snow tires. With a little bit of information, you can be a much more informed consumer when you go tire shopping.
First, you want to find tires that are rated for snow and ice. "All-season" tires won't do it. Make sure that any tires you buy carry the "mountain and snowflake" symbol stamped on the sidewall. This means that the tires meet specific industry standards for winter driving.
Winter driving tires have several special characteristics. They are made of a different, softer rubber compound that does not harden in cold conditions. The tread blocks are deeper, and contain sharper edges to more effectively bite into snow and hold traction on ice.
Some winter tires use metal studs that are inserted into holes cast into the rubber. These studs are designed to dig into ice and provide traction, and they do that very well. The problem is that when there is no snow on the ground, studded tires wear away the pavement, leading to the ruts we find on many of our roads. Plus, a studded tire does not grip as well as a standard tire when it's not driving on ice, which is most of the time even in a snow storm.
According to the Washington State Department of Transportation, "From the standpoint of traction alone, studded tires, when new, often provide some benefit over other tire types on ice-covered roads when the temperature is near freezing. However, the advent of the new studless tires has diminished the marginal benefit, and recent studies suggest that the infrequent, narrow range of conditions necessary for benefit from studded tires may not outweigh their detrimental effect on traction in dry or wet conditions on certain pavement types."
Beyond reduced traction when not on ice, studded tires also reduce your fuel economy. Luckily tire science has been hard at work to provide a new alternative. Studless winter tires now provide excellent traction on all frozen surfaces.
Studless winter tires typically use a series of fine slices in the tread blocks known as "sipes" and extra-soft rubber to increase the tire's ability to conform to the road surface. Some studless winter tires also use a sponge effect to remove the thin layer of water on top of ice that makes it super slick. Studless tires may also include silicon particles cast into the rubber to help grip any surface.
The result is that studless winter tires can transform the winter driving experience from treacherous to trustworthy, especially when combined with a modern AWD system featuring traction and stability controls and anti-lock brakes.
One last thought — if you can possibly manage it, it's smart to invest in a second set of wheels for your winter tires. That way you can get your winter tires onto your car in minutes when the forecast calls for snow, rather than driving around for months on winter tires when they're not really needed. Used wheels can be purchased inexpensively at used tire shops, junkyards, and on Craigslist. Full sets of used winter tires mounted on wheels are also commonly available through those channels as well. Check with your mechanic or dealer for your car's precise wheel specifications.
One more thing, reports from around Portland last week told of some people who installed snow chains onto the rear wheels of front-wheel-drive vehicles. In all cases, snow chains should be put on the driven wheels. For most modern cars, that's the front. Check your owner's manual if you're not certain about your car.