Tire Rack.com

Winter Testing at the Arctic Circle: Studless Ice & Snow



September 6, 2009

Tires Tested:
Bridgestone Blizzak WS60 (Studless Ice & Snow 205/55R16 91R)
  • What We Liked: Excellent glare ice traction
  • What We'd Improve: A small increase in snow acceleration traction
  • Conclusion: A benchmark for the category, and still the best on slick ice
  • Latest Test Rank: 2nd
  • Previous Test Rank: Not previously tested
Continental ExtremeWinterContact (Studless Ice & Snow 205/55R16 94T)
  • What We Liked: Excellent snow traction
  • What We'd Improve: A small increase in glare ice traction
  • Conclusion: Challenges the benchmarks by delivering class-leading snow capability along with very good ice traction
  • Latest Test Rank: 1st
  • Previous Test Rank: Not previously tested
Michelin X-Ice Xi2 (Studless Ice & Snow 205/55R16 91T)
  • What We Liked: Good snow traction and solid wet road braking
  • What We'd Improve: Increase ice traction
  • Conclusion: Delivers a good balance of snow and ice traction that's competitive with the class leaders
  • Latest Test Rank: 3rd
  • Previous Test Rank: Not previously tested

Vehicles Used:
2008 BMW E90 320i Sedan, 2008 BMW E92 328i Coupe

Everyone who drives in the snow knows that winter road conditions are almost always changing. Every vehicle that passes through new-fallen snow either clears a path by blowing it away, churns it into slush or packs it down into ice depending on the weather conditions. What that means is you never know what you're going to find on the road up ahead. And just as changing weather and road conditions challenge us as we drive, they also prove challenging to conduct meaningful tire comparisons out on the open road.

In an effort to better control winter's conditions, members of the Tire Rack team traveled to Northern Sweden in late January, 2009 during the height of winter season. This region near the Arctic Circle is home to a number of dedicated winter test facilities used by vehicle and tire manufacturers from around the world. Here we found consistent cold temperatures, plenty of snow and well-prepared snow and ice surfaces - ideal conditions for conducting side-by-side tire comparisons. Our evaluation was comprehensive - comparing each tire's ability to accelerate, brake and drive through the snow and across ice. We conducted both objective tests measuring each tire's performance with sensitive on-board instruments, as well as gathered subjective ratings of how each tire felt from the driver's seat.

Our evaluation compared three Studless Ice & Snow winter tires, each designed with advanced tread compounds and highly evolved tread patterns to be the best for when winter conditions are the worst. We compared the Bridgestone Blizzak WS60, the Continental ExtremeWinterContact and Michelin's X-Ice Xi2. We used new 205/55R16 tires mounted on 16x7.0" wheels. Tires were broken in by driving them on clear roads for approximately 100 miles prior to testing in winter conditions.

Subjective Tests

Performance Drive Ratings - Snow Handling

Our subjective snow handling test is designed to simulate what you might find out in the real world driving on unplowed roads during a moderate snow fall. The 1.1 mile, modestly uphill course was covered with several inches of groomed snow on top of a packed snow and ice base and proved to challenge each tire's ability to accelerate, brake and turn. Our evaluation was conducted with the test vehicle's traction and stability control system switched off so the driver would feel how much grip, and all of the slip, each tire had. ABS brakes were used for consistency and safety.

In our snow conditions, the Continental ExtremeWinterContact provided very good overall traction and stable vehicle balance, delivering responsive steering, good acceleration traction and confident braking capability. The Michelin X-Ice Xi2 demonstrated good overall traction, but could not quite match the ExtremeWinterContact. The Bridgestone Blizzak WS60 was found to be very similar to the X-Ice Xi2 overall, but with slightly less acceleration and braking traction in our dynamic driving conditions.

Snow Handling
Rating Bridgestone Blizzak WS60 Continental ExtremeWinterContact Michelin X-Ice Xi2
Acceleration 6.00 7.00 6.25
Braking 6.00 7.00 6.50
Handling 6.00 7.00 6.00
Overall Subjective Snow Handling 6.00 7.00 6.25


Performance Drive Ratings - Ice Handling

The subjective ice evaluation was conducted on a flat 4/10ths mile handling course covered in natural ice. The mottled texture of the ice was chipped rough then lightly polished, much like the ice-covered Swedish roads found in the surrounding area where studded tire use is common and no road salt or traction sand is applied after the fresh snow is plowed. This leaves the local roads ice-covered for nearly the entire winter season. On the test course, the combination of sweeping corners and areas of acceleration and braking challenged each tire's ability to control the vehicle and provide confidence to the driver.

The Continental ExtremeWinterContact delivered very good overall traction and was found to be noticeably superior to the other two tires. Once it did slide, there was good reserve grip and traction recovered quickly - almost abruptly during lift-throttle maneuvers. The relatively high level of steering traction of the ExtremeWinterContact resulted in a small tendency towards modest oversteer in some situations.

The Bridgestone Blizzak WS60 proved very capable and stable, providing good overall grip levels with a small tendency towards gentle and safe understeer. The Michelin X-Ice Xi2 followed close behind with slightly less overall cornering traction and modest understeer when it reached its traction limit.

Ice Handling
Rating Bridgestone Blizzak WS60 Continental ExtremeWinterContact Michelin X-Ice Xi2
Acceleration 6.33 7.00 6.00
Braking 6.25 7.00 6.00
Handling 6.55 6.90 6.05
Overall Subjective Ice Handling 6.38 6.97 6.02


Objective Tests

In an effort to quantify the subjective impressions felt by our drivers, we also conducted a number of instrumented objective tests to evaluate differences in acceleration and braking traction. These tests used sensitive, on-board accelerometers and wheel speed sensors to measure just how much acceleration and braking traction each tire had. These tests were conducted on groomed snow, polished ice and clear asphalt surfaces, and averaged multiple samples to eliminate any variability in conditions.

Objective test scores are percentage based, using a popular Studless Ice & Snow tire as the reference (Bridgestone Blizzak WS60 scored as 100%). A score above 100% indicates performance better than the reference tire, while a score below 100% indicates performance below the reference.

Snow Acceleration Traction without Traction Control

This test measured each tire's wheel spin during hard acceleration without traction control or throttle modulation by the driver. An onboard accelerometer measures the longitudinal force as a wheel speed sensor measures slip at the drive wheels. Scores were generated by graphing acceleration force over wheel spin and calculating the area under the curve for 9-60% wheel spin.

Tire Line Percent Versus Reference
Bridgestone Blizzak WS60 100.0%
Continental ExtremeWinterContact 103.6%
Michelin X-Ice Xi2 100.8%


A close look at the data revealed all of the Studless Ice & Snow tires we tested developed very similar acceleration levels, with increasing acceleration force as wheel spin increased, with all reaching a plateau around 45% slip. Less wheel spin generated lower acceleration force while wheel spin greater than 45% produced gradually declining acceleration force. This shows how turning off the traction control in certain situations when using Studless Ice and Snow winter tires can be helpful, such as when trying to maintain vehicle momentum when churning through deep snow or when attempting to get a vehicle unstuck by rocking it back and forth. Most vehicle traction control systems will not allow enough wheel spin to utilize a winter tire's peak acceleration traction found at relatively high wheel spin levels.



Snow Acceleration with Traction Control

This test measured the time required to accelerate from a standstill to 12mph using the vehicle's traction control system to manage wheel spin.

Tire Line Percent Versus Reference
Bridgestone Blizzak WS60 100.0%
Continental ExtremeWinterContact 104.6%
Michelin X-Ice Xi2 104.8%


Snow Braking with ABS

This test measured the distance to stop from 25mph on a groomed snow surface using the vehicle's Antilock Brake System to control wheel lock up.

Tire Line Percent Versus Reference
Bridgestone Blizzak WS60 100.0%
Continental ExtremeWinterContact 100.3%
Michelin X-Ice Xi2 98.0%


Snow Handling Lap

This test captured the time required to cover the 1.1-mile snow handling course. The test was conducted with the vehicle's stability and traction control switched off. ABS brakes were used for consistency and safety.

Tire Line Percent Versus Reference
Bridgestone Blizzak WS60 100.0%
Continental ExtremeWinterContact 102.6%
Michelin X-Ice Xi2 100.5%


Ice Acceleration Traction with Traction Control

This test measured the time to accelerate a given distance on polished ice using the vehicle's traction control system to aid the driver in minimizing wheel spin.

Tire Line Percent Versus Reference
Bridgestone Blizzak WS60 100.0%
Continental ExtremeWinterContact 85.5%
Michelin X-Ice Xi2 82.3%


Ice Braking with ABS

This test measured the distance to stop from 10mph on a polished ice surface using the vehicle's Antilock Brake System to control wheel lock up.

Tire Line Percent Versus Reference
Bridgestone Blizzak WS60 100.0%
Continental ExtremeWinterContact 85.9%
Michelin X-Ice Xi2 84.9%


Ice Handling Lap

This test captured the time required to complete a lap of the .4-mile rough ice course. The test was conducted with the vehicle's stability and traction control switched off. ABS brakes were used for consistency and safety.

Tire Line Percent Versus Reference
Bridgestone Blizzak WS60 100.0%
Continental ExtremeWinterContact 106.5%
Michelin X-Ice Xi2 96.4%


Dry Road Braking with ABS

This test measured the distance to stop from 50mph on dry asphalt surface using the vehicle's Antilock Brake System to control wheel lock up.

Tire Line Percent Versus Reference
Bridgestone Blizzak WS60 100.0%
Continental ExtremeWinterContact 98.7%
Michelin X-Ice Xi2 96.7%


Wet Road Braking with ABS

This test measured the distance to stop from 50mph on wet asphalt surface using the vehicle's Antilock Brake System to control wheel lock up.

Tire Line Percent Versus Reference
Bridgestone Blizzak WS60 100.0%
Continental ExtremeWinterContact 101.0%
Michelin X-Ice Xi2 101.4%





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