A case for Winter Tires

If you’re in the Northern hemisphere, it’s currently winter, generally cold, unpleasant, and sub-freezing temperatures. The world however, won’t come to grinding halt just for the sake of comfort, with that, most people get to experience winter travel.

Ice and snow can make something as mundane as a casual walk, into a tricky and dangerous endeavor, especially when you aren’t wearing the proper footwear. By extension, driving your car can be the same.

During each winter commute on our roadways, I often see the majority of my fellow motorists hopelessly spinning and sliding their way through the various turns and intersections I encounter. In all but the very worst of conditions I don’t seem to have that problem, why is that? This rhetorical question as to why my vehicle doesn’t magically defy the laws of friction is very simple, I’ll sum it up as; “The proper equipment for the proper job.”

In short, my secret is winter tires.

It should some as no surprise, but to many, the simple concept of winter tires is viewed with the stigma of “an additional expense” or “unnecessary”. I know many drivers consider a vehicle as a driving appliance, a simple method of conveyance, and many people want that to cost as little as possible.

However cutting corners when it comes to safety is not something I even like to consider.

This attitude is being adopted across Canada as more and more Provinces are making it mandatory to have winter tires for operation of a motor vehicle during snowy months. I for one, applaud this approach. Before you shout me down, follow my reasoning here:

Why are All-season tires unsuited for severe winter conditions, like those encountered in Canada?

There are a variety of reasons, but the easy ones to explain involve tread design and rubber composition.

Think of the difference between a smooth soled fashion shoe and a rugged hiking boot, which one would you trust to walk down that snowy hill? Fact is, the relatively tight and smooth tread of the All-season tire fills with snow very rapidly, which means you are now trying to stop and turn with the equivalent of a ski, offering little in the area of traction. A snow designed tread is more open and will self-clean while driving, giving the jagged edges of the siped tire a clean bite into snow and ice.

The tire compound is very important too, an All-season tire is designed to give, among other things, good fuel economy and long life. The easy way to do this is by using a “hard” compound of rubber, which will be resistant to wear during the heat of summer months. However during the colder months, the tire will become very hard and will not flex or conform to the road surface as well, in result your tire will slide along like a hockey puck. The snow tire will have a softer compound which would wear out quickly during summer, but during the cold months of winter it remains compliant and offers remarkably improved grip.

That is just a fraction of the theory involved, but moving beyond that lets actually look at the difference in stopping performance.

Stopping Distances Tested at 50km/h (31 MPH)

 

Test Conditions:
- -20°C with 3 to 5 cm of compacted snow and ice on asphalt surface
- Vehicles equipped with automatic transmission and anti-lock brakes
- Tests in 4-wheel drive vehicle conducted in all-wheel drive mode

*Fournier L., Comparative Evaluation of Performance of All-Season tires and Winter tires, Ministry of Transportation, Quebec, 2002.

As you can see the two of the most popular car types, mini-vans and compacts have the worst stopping distances, about 51 meters compared to larger heavier vehicles at 43 meters. Switching to the common standard unit of measure, a compact car equipped with Winter tires will stop 38 feet shorter than All Season tires, that is over 2.5 car lengths sooner. In a panic stop that is the difference between, before the obstructed intersection, or becoming part of the pile-up.

You’ll also note that 50km/h is not very fast at all, in many cases city roads can be zoned for speeds up to and including 70-80 km/h. Highways often reach posted limits of 110 km/h, as a safe practice you should reduce your driving speed for conditions, however this is not always the habit of some drivers. As such, the importance of winter tires for stopping and car control increases with driving speed.

-But I have ABS/TCS/etc.

While these modern driving aids are a great help, they are a support system for the driver and should not be relied on a substitute for good driving habits and proper equipment. ABS will actually post a longer stopping distance over a properly used non-ABS car, but ABS allows you to steer without locking the wheels. In low-traction conditions the ABS system will only apply as much brake force as it takes not to lock the wheel, with a set of All-Season hockey pucks, imagine how little braking action that takes.

Traction Control typically only assists during acceleration and it applies much like ABS. Most systems still allow some spin, so anything that enhances basic traction will help the TCS work correctly.

About wheel-spin, ever wonder why approaches to intersections are so slippery? It’s mainly a two-fold effect, one part is heat from stationary vehicles melting accumulated ice and snow every so slightly. The second part is the fresh ice/water mix is polished to a glass-like sheen by the All-Season equipped vehicles struggling for grip. This one-two combination is much like the effect of a Zamboni machine at a hockey rink, and the result is the exact same. A good winter tire will help you not contribute to the problem and allow you to better cope with conditions at that next intersection.

Another common thought is that winter tires are very expensive, and much like anything vehicle related, they can be, but not if you shop around. Some of the most inexpensive tires I’ve purchased have been winter tires, when the winter season approaches watch for sales and deep discounts. During a follow-up article I’ll discuss various tire options and buying tip to minimize costs.

When it all comes down to it, your car’s tires only touch the pavement with an area about the size of the palm of your hand, and when it comes down to stopping or turning, how would you like to do it? Like you’re in control, or like you’re riding a crazy carpet?

The choice is obvious for me.