February 27, 2007
Michelin X-Ice. Click image to enlarge
Article and photo by Paul Williams
Many of today’s vehicles possess an impressive amount of technology to improve handling and to protect occupants in the event of an accident. This technology is becoming a key selling point when consumers are shopping for a vehicle, and that’s certainly to be applauded. But it can lead to a false sense of security, according to Normand Laremouille, Michelin’s Winter Segment Marketing Manager for North America.
Indeed, all the stability technology available can’t make up for poor tire condition, or incorrect tire selection. My brother recently learned this as his family’s Kia Sportage compact SUV — equipped with electronic stability control, anti-lock brakes and traction control – sailed through an icy intersection completely out of control.
Baby Simone was properly accommodated in a car seat, oblivious to the surrounding events; her seatbelted mother was in the rear seat beside her, wide eyed with fear.
“Nothing worked,” said my incredulous brother afterwards. “The stability control, the ABS, nothing came on and I had no steering or brakes.”
A minor collision with another vehicle did occur. It could have been a lot worse, and it was only a few days later that virtually the same thing happened again. My brother thought it was the brakes; somebody else thought tire pressure.
All those electronic systems would have worked, it turned out, if the tires – original equipment tires, with 50,000 km on them – had enough grip on the slippery surface. Even though good tread was visible, and the tires were “within specification,” according to the dealer, their all-season compound had likely become hard in the unusually cold weather. This and the accumulated tread wear was no match for the icy roads prevalent in Niagara this winter.
So when my brother hit the brakes, it’s a good bet that the wheels either stopped rotating because the surface was too slippery for the tires to find any purchase, or they repeatedly stopped and started, trying to find traction. Either way, none of the stability systems worked as expected until a set of new winter tires was mounted on the Sportage.
“It’s like night and day,” says my brother. “The difference is incredible.”
The difference is that the traction control, anti-lock brakes and stability control now work as designed, and the vehicle responds to steering and braking inputs even on icy surfaces.
Of course, tire manufacturers already know this. Last winter, Michelin conducted a test at York University in Toronto, where identical cars were driven on one of the hockey rinks there. The cars were equipped with stability control, traction control and anti-lock brakes but some used Michelin all-season tires and others used Michelin X-Ice winter tires.
Mr. Laremouille describes how the cars behaved:
“Time and again, the cars with the all-season tires would lose control. Even with stability control, the back end would slide out, or the brakes would lock. But with the winter tires this didn’t happen.”
As Mr. Laremouille points out, “It’s the tire that stops the car, not the wheel.”
One of the biggest differences between winter tires and all-season tires is that winter tires like the Michelin X-Ice use a softer rubber compound to increase grip. As you might expect, a softer tire will allow the tread blocks and siping (small cuts) in the tire to maintain their flexibility as they travel over the road surface, compared with a hard, frozen tire that simply slides over ice and snow like a frozen hockey puck. However, the X-Ice also uses a hard compound that’s embedded inside the treadblocks to improve handling.
Michelin calls this ability to provide grip and handling through the life of the tire “Advanced Progressive Stiffness” (ASP). Mr. Laremouille explains that ASP enables the tire to maintain its flexibility and tractive qualities even as the tire wears, and suggests that an X-Ice tire will continue to perform as designed down to 4/32-inch remaining tread depth (a new tire has 10/32 or 11/32-inch tread depth). In short, the X-Ice tire is designed to perform as intended throughout its service life.
Michelin suggests that a winter tire will deliver up to 25% more traction on winter roads, and this is corroborated by the traction tests conducted by www.Autos.ca in 2006. In fact, of all the benefits experienced with the use of winter tires during our Traction 2006 event, an improvement in braking was the most obvious.
And that’s what my brother thought he needed: brakes.
But what he really needed, although he didn’t know it at the time, was a set of winter tires.
Michelin X-Ice tires are available in 54 sizes, ranging from 13-19-inch rim diameters. Michelin Latitude X-Ice tires were developed specifically for SUVs, and are available in 23 sizes, from 15-18-inch rim diameters.
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