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September 9, 2008
Nokian Hakkapilitta RSi (Studless Ice & Snow)
Today's winter / snow tires have come a long way from the "snow tires" our grandparents and parents used to use on the back of the family car or station wagon. Those old winter tire designs relied on deep, aggressive tread patterns that weren't all that far removed from off-road implement tires of the day to cope with the slush and snow of winter. But excessive road noise, limited snow traction and relatively poor ice grip were byproducts in order to get somewhat better winter traction than their summer or all-season tires could provide. Thankfully, technology marches on, as evident in today's Studless Ice & Snow winter / snow tires.
In an effort to keep raising the bar for wintertime capability, Michelin has introduced the X-Ice Xi2 Studless Ice & Snow winter tire, a clean-sheet design that replaces their popular X-Ice tire line. Building on the original X-Ice's stable clear road handling and good ice and packed snow traction, Michelin has designed the new X-Ice Xi2 to noticeably improve deep snow and ice traction without the typical trade-offs in clear road handling or tread wear.
Because the Michelin X-Ice Xi2 was introduced to tire dealers and members of the media before it was available to the public, select members of the Tire Rack team were invited to the Mecaglisse track located 1.5 hours north of Montreal, Quebec, Canada. There they experienced the winter performance of Michelin's latest studless winter / snow tire -- the X-Ice Xi2. This modest complex features a variety of handling circuits cut into the rolling fields, each with a thick ice base and most with plenty of packed or loose snow on top. Unfortunately, our experience did not provide an opportunity to evaluate the X-Ice Xi2's clear road manners or gauge treadwear.
The day broke clear and crisp with cold temperatures overnight that turned the prior day's fresh snowfall into a frozen concoction of crystallized powder. Morning temperatures hovered around +5° Fahrenheit (-15° Celsius) with clear blue sky and zero wind. A perfect morning for testing winter / snow tires in their element. The evaluation consisted of three basic exercises: ice braking and acceleration, packed snow handling and medium (loose) snow handling. This evaluation used 2008 Volvo sedans all riding on 205/55R16 tires inflated to the vehicle manufacturer's recommended pressures.
The first course features a groomed, rough ice surface to evaluate acceleration and stopping traction. Connecting the start and finish line was a simple, sweeping 4-turn handling course that allowed for evaluation of the subjective cornering traction on an icy surface. For these exercises we used 2008 Volvo all-wheel drive sedans. The vehicle's traction, stability and anti-lock brake systems (ABS) were left engaged to help eliminate human variables and maximize the traction each tire was able to provide.
First up, ABS-assisted stopping on ice. Our team took turns accelerating to 35kph (22mph) on the ice surface, followed by a hard application of the brakes at a preset point using maximum pedal pressure to engage the vehicle's ABS system. Marker cones on the side of the braking lane served as a reference to compare the stopping distance of each tire. While our schedule did not allow for enough runs to constitute a proper scientific test to measure the ice stopping distances, general impressions were readily apparent, with the Bridgestone and Michelin tires stopping in the shortest distance. The Nokian was very close, taking a few extra feet to stop the vehicle, while the Goodyear rounded out the group taking nearly a full car length longer to stop. Driving the return handling course revealed a similar trend, again with the Bridgestone and Michelin tires showing a modest advantage over the other two tires. The Nokian delivered good ice traction, while the Goodyear showed the least traction of the group and took longest to regain grip once the traction limit was exceeded.
Next came the acceleration test that began with a standing start. Upon the go signal a stopwatch was triggered to measure the approximate time needed to accelerate down the 100 meter (328 feet) icy lane. The driver's objective was to accelerate as fast as possible towards the end marker, relying on the tire and the Volvo's sophisticated AWD system and traction control electronics to maximize acceleration and minimize the time needed to travel the distance. The stop watch couldn't provide accurate enough results to report, but did provide some feedback to support the subjective feel from the driver's seat. Combined with the Volvo's sophisticated AWD system and traction control, all four tires in this evaluation allowed the vehicle to accelerate rather quickly. Here the Michelin showed a slight advantage over the other three, providing superior traction at the initial start, which helped this vehicle get rolling faster and take advantage of its excellent grip all the way down the course. The Bridgestone also displayed excellent traction once the vehicle was rolling, but needed more driver discretion when applying the throttle at the start line. Subjectively, the Nokian was third with the Goodyear rounding out the group.
Moving over to the handling circuit with its packed snow surface on top of an ice base, we changed vehicles, this time using 2008 Volvo front-wheel drive sedans. Again traction, stability and ABS braking systems were left active to aid the drivers in negotiating the twisty and undulating road surface of this course as quickly as possible. With multiple laps already on the track, the packed snow surface was churned into 2-3" of loose snow on top of packed snow, with some ice spots appearing in the corners and braking zones. While the laps were not timed, the Michelin X-Ice Xi2 felt as though it had a slight advantage over the rest of the group, delivering predictable handling and excellent acceleration, braking and cornering traction, even around the tight, icy hairpin corner near the finish. The Bridgestone Blizzak WS60 was a close second, also offering excellent traction. The only subjective difference between these two was the manner in which the car and tires behaved at the limit. The X-Ice Xi2 gave plenty of warning as it reached its traction limit, while the WS60 would reach the limit somewhat more abruptly, resulting in gentle understeer or oversteer depending on driver input and vehicle weight transfer. The Nokian tire was not far behind the Bridgestone, offering competitive snow traction. This tire displayed a progressive feel at the limit with both front and rear tires losing grip simultaneously, resulting in a neutral balance that was easy to manage and control. The sliding factor of this tire made it the most fun to drive, but in the end it didn't offer quite the overall traction of the Michelin or Bridgestone tires. The Goodyear followed, with slower steering response as well as longer recovery time once traction was lost.
The final exercise was in deeper "medium" snow, where the tire would leave a full depth imprint as it rolled through the 4+" of loose snow on the track. This circuit was a small kidney-shaped oval driven at relatively steady cornering speed and featuring a small down/up hill just before the start/finish line. Once again, the Michelin proved to have the edge, feeling slightly more predictable and stable as it chewed its way through the deeper snow. The Bridgestone was a very close second, with just slightly less overall traction and predictability than the Michelin. The Nokian displayed its trademark balanced handling, just with a modestly lower overall grip level than the Bridgestone. The Goodyear rounded out the group requiring slower cornering speeds and greater patience and smoothness of steering, throttle and brake inputs.
Bridgestone Blizzak WS60 (Studless Ice & Snow): The Blizzak WS60 is Bridgestone's Studless Ice & Snow winter tire developed for the drivers of coupes, sedans, minivans and crossover vehicles looking for traction on winter's slushy, snow-covered and icy roads. The Blizzak WS60 represents the third generation of Bridgestone WinterBiter tires designed to deliver wintertime traction and control that inspires driver confidence by getting the most out of the vehicle's potential. Read more.
Goodyear Ultra Grip Ice (Studless Ice & Snow): What type of winter performance would you expect from tires designed for use in North America, manufactured in Canada and introduced in the Swiss Alps. If your answer is enhanced snow and ice traction, you'd be right and you'd be describing Goodyear's Ultra Grip Ice winter / snow tires which are designed to provide traction during winter's most severe, icy conditions. Read more.
Michelin X-Ice Xi2 (Studless Ice & Snow): The X-Ice Xi2 is Michelin's Studless Ice & Snow winter tire developed for the drivers of coupes, sedans and family vans that want to combine enhanced ice and snow traction with predictable wet and dry road handling. The X-Ice Xi2 is designed to tackle the coldest winter driving conditions around the world. Read more.
Nokian Hakkapilitta RSi (Studless Ice & Snow): Additional info not available.