Use proper tires for conditions during the winter

Hey there, time traveller!
This article was published 14/11/2003 (8178 days ago), so information in it may no longer be current.

THE good news is that 81 per cent of Canadian drivers recognize the need to slow down and leave more room between vehicles in winter driving.

The bad news is that most grossly underestimate how big that space should be.

That’s the word from Uniroyal’s Tire Doctor, Roger Stapley, quoting a J.D. Power survey commissioned by Uniroyal.

Stapley said that at 40 km-h, a vehicle travels 2.2 car lengths per second, which puts a safe following distance in summer at 4.5 car lengths. In winter, that grows to eight or nine car lengths.

He said most people understand that. But when he asks average drivers in driving clinics to stop 4 car lengths behind a car, “they’ll do two-and-a-half.”

“So they don’t know what a good distance is and then can’t visualize it correctly anyway,” he said.

And, of course, all this is on winter tires in good condition. Start adding space if you’re driving on all-seasons or on winter tires near the end of their treadlife.

Stapley was in town as part of a cross-country media tour discussing driving safety and, of course, promoting tires.

Stapley has a vested interest in promoting winter tires, but he’s not alone. Automotive Showcase’s Alan Sidorov and Richard Russell both sing the praises of using dedicated severe service winter tires, as does Bill Ward, a veteran driving instructor who is the principal behind the Vehicle Research Centre at St. Andrews Airport.

In a nutshell, here’s why: winter tires are formulated to remain flexible even in severe cold. Stapley says current winter tires get stiff at -35C. All-season tires, in contrast, begin to lose flexibilty — what engineers call the glass transition point — at 7C. As in above zero. As in a nice fall day in Winnipeg.

As well, the tread design of winter tires both bites through snow better and grips ice better than all-seasons.

For 30 years, the tire industry has worked to convince us that all-season tires offered year-round performance and freed us from the twice-yearly ritual of changing tires.

What gives?

Now they’re back at selling winter tires. What gives?

Stapley said the history of all-season tires goes back to the early 1970s and the switch from bias-ply tire construction to radial-ply construction. (Ply refers to the fabric innards of a tire: bias-ply tires were built with small pieces of fabric laid with the threads on the bias and overlapped each other all the way around the tire. Radials have their threads running perpendicular to rotation from one bead to another.)

The change meant tires that provided greater contact surfaces and allowed for more aggressive tread designs. And that also meant that the worst all-season radial was better than the best bias-ply winter tire, Stapley said.

So it was for 30 years. Then, he said, new tire compounds and tread designs were developed that allowed tires to stay flexible in the cold and bite into ice better.

Stapley said that to earn a severe service designation (the snowflake and mountain symbol), tires must provide a 10 per cent traction advantage in winter conditions and 30 per cent in ice and snow.

Unlike the M+S symbol (mud and snow), which is determined only by meeting certain design criteria, the severe service designation must be earned through independent testing.

The keys to winter tires, he said, are more pronounced zig-zags in the circumferential grooves and sipes, or tiny cuts that run the depth of the tread.

The sipes open and close as the tire rotates and that provides a suction action on ice.

Resistance to purchasing winter tires, Stapley suggests, is based on a couple of things. The first is a reluctance to spend the $600-$800 winter tires (when mounted on their own rims) cost and face the inconvenience of a twice-yearly changover. Also, some people just don’t recognize the advantages, he said.

Studs a wash

Studded tires are best on snow and ice, but Stapley doesn’t recommend them for most city drivers. On most winter days in Winnipeg, main streets are cleared down to the pavement. Studs are worse on bare pavement than all-season tires.

But the tradeoff comes at about 30 per cent. If only 30 per cent of driving is on cleared streets with the remainder on snow-covered or icy roads, he’d suggest moving to studs.

Stapley also points out that over the course of your tires’ lifespans, the cost is the same. By splitting wear-and-tear to two sets of tires, you extend the lifespan of each. The key is having the snow tires mounted on their own rims.

That increases the initial cost but pays for itself very quickly. Dismounting and remounting four tires on the same rims costs about $80. Twice a year, that’s $160. Merely switching wheels (tires and rims) costs $25, but since you have to rotate your tires twice yearly anyway, doing the switch in concert with the rotation virtually eliminates that cost from the cost of winter tires.

After three years, the person with dedicated winter rims has spent $350 (including the $25 each rotation charge) while the person who didn’t spring for new rims has spent $480.

Storage of the unused set isn’t difficult. Some will say that you have to store the tires vertically, but Stapley has seen no evidence favouring stacking or standing. The key is keeping them away from electric motors, petroleum products and extremes of heat.

(Electric motors produce ozone, which breaks down rubber.)

Of course, storage is a problem for apartment dwellers and those with small houses, but some tire shops offer storage as part of the winter tire package.