The reason is also simple. All-season tires are a compromise: You don't expect them to deliver the same cornering potential on pavement as dedicated performance tires, and likewise, they can't match the slippery-road traction of today's winter tires. "The difference between an all-season tire and a snow tire," notes Matt Edmonds, director of marketing for The Tire Rack, "is the same as between an all-season tire and a performance tire. It's that much better."
More Europeans seem to have gotten the message. According to statistics provided by Goodyear, for instance, about 80 percent of drivers in Scandinavia switched to dedicated winter tires during the "dark months." About half of Austrian and Swiss drivers and nearly one-third of German car owners also mount up winter tires when the weather turns cold.
In terms of sheer traction, studded tires still provide the best grip. Goodyear estimates that a metal-studded tire provides up to 40 percent greater traction on hard-packed snow and ice than all-season tires. However, they also have a definite downside, producing higher noise levels, decreased ride comfort, and reduced traction on both dry and wet (but non-freezing) road surfaces. Plus, they're well known for chewing up asphalt, leading many regional governments to ban their use.
By contrast, a modern studless snow tire can provide up to 20 percent better snow traction than an all-season design, without the significant disadvantages of studs. We've verified this from behind the steering wheel. A well designed winter tire provides a tangible seat-of-the-pants performance advantage over all-season tires in both snow and ice conditions. This includes better initial hookup, shorter braking distances, and cornering that's both more predictable and controllable. This is important, since again according to Goodyear, "The largest group of [winter] accidents results from loss of lateral control of the car on ice and snow."
The key word in snow traction is "bite." The more edges, the better. What you generally get in a good winter tire is an aggressive tread design, deep grooves, sharp corners and edges for digging into snow and gripping ice, and plenty of sipes (the small slits within individual tread blocks). Sipes provide two advantages, they help keep the tread blocks flexible in freezing conditions and provide additional small, but helpful edges.
In the past year, the Rubber Manufacturers Association instituted stricter requirements for tires designated for severe winter conditions. Only tires that meet these requirements can display the letters M and S in some configuration, plus a pictograph of a mountain with a snowflake. If unsure about whether a tire model is rated for severe snow conditions, look for this symbol.
There are plenty of good snow tires on the market. In fact, tire manufacturers often produce a variety of designs to fit different types of vehicles and driving conditions. Dunlop, for instance, produces the SP Winter Sport M2 for T- and H-rated high-performance vehicle fitments, the Graspic HS Q-rated performance radial, the SP Winter Studdable, and the Grandtrek SJ4 studless design for use on SUVs, light trucks, and vans. Pirelli, meanwhile, offers its Winter Ice and Winter Ice Plus models in both a conventional directional tread design, as well as a special asymmetrical pattern designed to use the inner tread area to optimize traction and braking and the outer area for cornering control and directional stability.
It was Bridgestone, however, that really launched the modern era of winter tires when, in 1993, it introduced its innovative Blizzak design with a unique multicell compound. This fall the next-generation Blizzak will hit the market in three new models. The direct replacement for the original Blizzak WS-15 is the WS-50, which has a new tread design and a new Tube Multicell compound claimed to offer better snow and ice traction. In addition, the two-layer tread now has conventional snow-tire compound under the multicell outer layer, instead of the all-season compound previously used.
There are also now two ice-compound versions of the Blizzak. Called The IceGripper and designated MZ-01 and MZ-02, these use a slightly softer Link Multicell compound that provides better handling and braking on ice. The MZ-01 has a larger circumferential groove for better wet performance than the MZ-02. Bridgestone is also now offering the Winter Dueler, a snow tire using Blizzak technology that's targeted for light trucks and sport/utility vehicles.
Meanwhile, Goodyear's latest offering is its Ultra Grip Ice, which combines a directional tread with a special silica tread compound, called IceLoc, to provide up to a claimed 12-percent better ice traction than a conventional snow tire. Like the Blizzak, the Ultra Grip Ice uses a two-layer compound, with its IceLoc compound on the outside and a conventional snow-tire compound underneath. The Ultra Grip also employs a wider, flatter tread, and high-density sipes keep the tread face pliant in freezing temperatures, while helping evacuate the film of water just below the snow.
Michelin's Arctic Alpin brings a whole new concept to the market with over 1700 Torque-Locking Sipes. In contrast to conventional sipes, which descend into the tread block as a straight cut, Michelin's design has a zigzag pattern. This allows the thin blocks of rubber between the sipes to squeeze together and interlock with each other under load, providing more stability to the individual blocks and ribs. The result is that, even on clear roads, the tire still provides good handling and response. With the Arctic Alpin, the winter compounding extends throughout the depth of the tread.
Like the popular Blizzak, Yokohama's Guardex series also employs a micro-pore type compound, but one that runs throughout the tread, not only on the outer layer. In addition, it features nylon "mini-stud" fibers in the tread, which are designed to improve snow traction, wear, and dry-handling capabilities, as well as provide the extra bite of studs, but without the damage.
Yes, the winter tire market is heating up with a variety of good designs to help you get through the slippery stuff. But perhaps the most important thing is that you make the switch to a winter tire at all. The extra performance, control, and safety are waiting to be enjoyed.
While we'd wager that 99.9 percent of our readership can't thread a cross-ice pass through traffic like Wayne Gretzky, we're not so sure about the Great One's credentials for winter driving (more so, say, than any other person growing up in the snowbelt). Still, Goodyear has teamed up with Gretzky to promote the performance advantages of winter tires in a new ad campaign. As part of this, Gretzky and J.O. Hunt, chief engineer for Goodyear tires, offer these 10 tips for winter driving.
1. Slow down. Wet, snowy, or icy roads offer less traction and make it harder to stop and turn.
2. Consider buying a set of winter tires. It's best to replace all four tires with winter tires because differences in tire size and wear can negatively affect a car's handling and stability.
3. Beware of bridges: Because bridges and overpasses are exposed to cold air both above and below, ice can form on them even when the roads on either side are free from ice.
4. If possible, carry a sack of sand or gravel in the trunk. On a rear-drive car, the added weight over the drive wheels will improve traction. And the sand or gravel can be used to help get you out if you become stuck.
5. Avoid sudden inputs on the steering wheel, brakes, or accelerator. Make gradual movements to avoid upsetting the balance of the car.
6. The buildup of ice and mud on wheels and underneath your car can cause your wheels to become unbalanced, which can upset the ride and lead to unnecessary wear of your tires and suspension parts. Wash off any mud or ice as soon as possible.
7. If you're planning a long winter trip, pack extra blankets, water, food, and a few chemical-heating packs in case you get stranded. If you do get stuck, stay with your vehicle until help arrives.
8. Have your cooling system fully checked out, including coolant, hoses, belts, and water pump.
9. Maintain your tires at proper inflation to maximize their contact with the road. Pressure that's too high or low can cause unnecessary tire wear and reduce the size of the contact patch, making it less safe.
10. In snowy conditions, make sure your car's air intake is free from a buildup of snow. Many cars draw air from below the radiator; if this intake becomes clogged with snow, you car could overheat, even on a cold winter day.
Courtesy of Motortrend
