This last weekend a friend and I entered a heated discussion about winter tires - see what I did there?
This friend is one of the many people here in Quebec who waits until the last days before winter tires are mandatory by law to change his car. I’m one of those who changes sooner rather than later. We clashed - amicably, we’re still friends.
By law, Quebec car owners are required to have winter tires installed by December 15th. Regardless of the weather situation, no police officer can give you a ticket if you don’t have WT before it. There’s a discussion to bring this date earlier - a move I completely agree on - but unfortunately there’s a lot of people who think like my friend. So, I thought it would be nice to have a more comprehensive list of arguments on the importance of winter tires and why you should install them according to the weather, not to the law.
First things first: this discussion will be completely lost on anyone living on a place where the thermometer never goes below 7ºC. I remember the days when, living in Brazil, the only reason to change the tires on a car was damage or severe use.
The confusion about winter tires are, in part, a market’s fault. The non-winter tires are called either all-season tires or 4-season tires. That’s the main argument my friend have to not install his winter tires before the lawful date. In my friend’s words:
"They are called all-season! Winter is part of this! I’m sure we don’t even really have to change the tires, it’s all a conspiracy between the tires industry, the garages and government!
But it really isn’t. It comes down to three main factors:
Temperature: The rubber compound is different in winter tires and all-season tires. Specifically, the rubber on all-season are harder than on winter ones, because this provides greater tread life - meaning, it’ll take longer for the treads to disappear. But that also means all-seasons get even harder in cold temperatures. Below 7ºC, they get so hard they become stiff. And why does it matter? The tire should have a healthy surface contact with the ground to provide proper grip. A harder tire will flex less, keeping more of its round shape, and touching the ground less. It will not only make it harder for your car to transform the tire movement into traction - increasing your fuel consumption - but it will also make it more difficult to stop and turn the car. Imagine that in a snowed road, which already have less grip than normal, and you can see the recipe for disaster. This is also why it’s so important to keep your tires properly inflated. Too much and you’ll lose surface contact. Too little and the surface contact will be so large it will demand more energy to move the car - thus more fuel being burned.
Tread depth: The treads on all-seasons are designed for dry and wet roads. They are shallow, because most roads are already very good in keeping a low water layer. The treads need only to get a little water out of the way so most of the tire touches the ground. Winter tires have deeper treads, to try and “eat” as much snow as possible when it’s the case - since snow doesn’t really leave the roads unless human action is taken or the weather warms, allowing the tire to touch the ground if possible. If not, the pressure on the higher parts of the tire will grip better.
Tread design: Treads on all-seasons are designed for evacuating water. They are basically useless in snow. Winter tires have treads designed to grip the snow - some claim to be able to evacuate snow as well, but that’s debatable. The treads on winter tires must provide good traction on snow.
Montreal had its first snow of the season around mid-November. Temperatures have been below 7ºC for several weeks now. We just had a black ice situation and the winter isn’t even officially here yet. I was able to convince my friend, who promised to change his tires this week - which is still only one week earlier than what he intended to do, but still.
So, whatever the law demands where you live, pay closer attention to the weather, because it’s the real gauge for when to change your tires.
Keep safe out there!