From www.suv.com/EDU/WinterDriving/
With increasing restrictions on studded snow tires since the mid-1980's- especially in the U.S.-Bridgestone has become the leading manufacturer of studless "ice tires" for passenger cars. And, in 1992, this tire company developed the first winter tire for the SUV and light truck market when tests had demonstrated that these vehicles, because of their weight and design dynamics, showed poorer handling with slippery and low-traction conditions on all-season tires, even when equipped with four-wheel drive.
The original Blizzak WS-15 featured a multi-cellular compound --rubber with tiny pores -- which displaced the thin film of water that forms between the tire and ice surface. Additionally, Blizzak's zig-zag patterned tread creates a biting edge that improves grip and is rated for speeds of between 60 and 80 mph. In the first seven years, Blizzak sales were over 50 million in 15 countries.
Blizzak comes now in three formats to meet various vehicle and climate differences. The WS-50 "WinterBiter"is an updated version of the WS-15 that has been designed for heavy-snow areas. Setting it apart are a new "Tube" multicell compound in addition to it pores, which give more durability. The WS-50 is recommended for both cars and minivans.
The MZ-01 and MZ-02 "IceGripper" models are designed for drivers who live in regions that get a mix of precipitation and ice. Specialized for peak performance, the tread pattern has a large circumferential groove that dissipates water quickly. These models feature "Link" multicell technology that makes these tires especially soft and adept on the ice.
The biggest news, however, has been the Winter Dueler, which applies the proven Blizzak technology to a light truck/SUV tire. While today's popular sport-utilities inspire confidence in winter weather, four-wheel drive doesn't help when trying to stop or corner on snow or ice or other low-traction surfaces. As with passenger-car tires, the all-season or even "all-terrain" rubber on the typical SUV is designed primarily for ride comfort, long wear, and fuel economy while compromising snow traction. The Winter Dueler comes in metric, P-metric, LT-metric, and flotation sizes to fit sport-utes large and small, from the Lincoln Navigator to the Toyota RAV4.
Short treadlife has always been an issue with snow tires. On all Blizzaks, approximately 55% of the tread is the ice-gripping Multicell compound. With the original WS-15, the remaining 45% of the tread was a conventional all-season material, allowing the user to keep the tires on the vehicle after their final winter season. On the new generation Blizzaks, however, the last 45% of the tread is designed for winter use, though not as an ice tire. The standard UTQG (Uniform Tire Quality Grading - a treadlife measure) does not apply to winter tires.
