Auto Service World
Feature   March 1, 2007   by Jim Anderton, Technical Editor

Why Skid?

Bridgestone's Blizzak WS60 replaces a winter favourite

Every tire company has a product or line that stands out amongst the firm’s other offerings, either by performance, reputation, or just consumer brand recognition. For Bridgestone’s winter lineup, that tire was the WS50.

A favourite of serious winter drivers and ice racers, the WS50 is reaching the end of the road, so to speak. Until now, the alternate choices from Bridgestone were aimed at the polar ends of the winter tire spectrum: urban/suburban sedan and SUVs, and the more muscular light truck segment. That gap has been effectively closed with the launch of the firm’s new Blizzak WS60, unveiled at the Bridgestone Winter Driving School at the Center for Driving Sciences in picturesque Steamboat Springs, Colo. Going to the U.S. to test winter tires might seem irrational, but the ski country of Colorado in late January is as close to a Canadian winter as you’ll find in the “Lower 48,” and the Winter Driving School’s ice track provides a combination of ice and packed snow that are perfect for wringing out new rubber.

What makes the WS60 new? No tire company launches major new products without a parade of technology, and Bridgestone is no exception. This year, it is nanotechnology — something that the tire industry was doing long before sci-fi made it a popular buzzword — “NanoPro-Tech.” This proprietary technology controls the interaction between polymer, filler materials (carbon black, and for high quality winter and performance radials, silica) and other rubber chemicals at the molecular level. The idea is to get the “filler” materials to react chemically with the rubber they’re blended with, rather than just dispersed within the rubber like seeds in a watermelon. The rubber compound that achieves this is called “RC Polymer” a butadiene rubber that is specifically designed to react with silica. It’s part of the overall tread rubber compound, improving tread flexibility for enhanced wet and snow traction.

Also, in the WS60’s tech portfolio is Bridgestone’s familiar Tube Multicell compound, which wicks water away from the tire’s contact patch. Tube Multicell is enhanced in the WS60 with “bite particles” which are attached to the tubes of the Multicell compound by a special coating. As the name implies, the bite particles grab icy surfaces for enhanced grip. Canadians who have driven in real cold, the familiar and feared Alcan Highway cold, know that ice can be as hard and grippy as dry pavement; tires can squeal on very cold, hard ice. The rest of us operate in a winter where the vehicle’s weight compresses and melts the ice momentarily under the tire’s contact patch, making ice grip as much about clearing water as a rain tire does.

That’s why so many ice radials have a decidedly “all-season” look about it. The Blizzak WS60 uses 3-D zigzag sipes to clear water, along with the Tube Multicell tread compound. The WS60 uses a “cap and base” tread construction, with tread depth indicators at the 50 per cent wear mark, letting the motorist know that only 10 per cent of the remaining tread is the compound. What’s left still works as a conventional winter tire, but with a reduced grip.

How does it work? On the Winter Driving School ice track, the tire performed very well, gripping laterally and in straight line acceleration and stopping, as well as digging out of packed snow despite a tread pattern that’s decidedly less aggressive than the WS50. That’s surprising since the tread of the WS60 is much less “lugged” at the shoulder, giving the tire the appearance that it has a narrower contact patch. That in fact may be one secret to the tire’s success: A long narrow contact patch delays hydroplaning-derived loss of control much better than the short, wide patch typical of modern, wider radials. A side benefit is a much quieter ride, noise being the major issue with the previous tire’s dry road hum. Within Bridgestone’s winter lineup, the Blizzak Revo1 was the quieter option, although that tire was less adept in deep snow than the WS50. Hard-core winter drivers expect noise in serious winter radials, but the ability to quiet the tire without giving up performance should broaden the consumer base for the Blizzak WS60 into Revo1 territory. When pressed on the potential market overlap, Bridgesone’s Phil Pacsi, vice-president of consumer tire marketing simply stated the Blizzak WS60 will eventually replace both the Revo1 and WS50.

It’s a logical marketing move that might also relieve a little of the inventory pressure that dealers feel every winter, especially with the continuing size proliferation from auto manufacturers. I’ll take a banshee wail from all four corners to get five per cent more grip, but real consumers will likely prefer grip with good manners. The Blizzak WS60 is a lot tougher than it looks, mainly because the tire replaces old fashioned “tooth and claw” tread designs with technology. All this begs the question about a future WS70: More technology with a kinder, gentler look or back to a brute force, saber-tooth tire? Stay tuned.

The Bridgestone Blizzak WS60 rolls out for consumers for the 2007-2008 winter driving season, in 38 R-speed rated sizes in the 70 to 45 series ranging from 14 to 17 inch.

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