When you think of winter tires and how they work, the first thing you probably think of is the tread. They’ve got big, chunky blocks for digging into snow and lots of tiny, little, zigzag sipes for traction on ice. After all, this tread design’s why they work so well, right?
While this is true, winter tire manufacturers actually have another trick up their sleeve to make tires even stickier in cold weather:
Specifically, chemistry. You see, the tire compound can play a big part in traction, and tire manufacturers are always looking for ways to improve. There’s not a lot of room for improvement in the winter tread design, it’s been tried and tested for more than half a decade. But the compound is another story, and the engineers hit the jackpot when they started adding silica to the tread.
Silica as a Filler
So what is silica? The name makes it sound kind of sci-fi, but it actually just comes from sand. We’re not even talking special sand or anything. Just regular, old sand from pretty much any beach has silica in it.
Silica does several sciency things that make it useful in tire compounds. For example, it makes some of the molecules in the compound stick to each other better than they would on their own. This is why it’s used as a filler in tire compounds, along with carbon black. You may have heard of carbon black, as it’s the most well known tire filler and it’s responsible for making tires, well, black.
The best-known filler in tires is carbon black. It’s plentiful too, because it’s a byproduct of carbon fuels, including oil and coal. Carbon black, which gives tires their color, hardens the rubber compound. It helps to create friction between the tire and the road. That’s good, because it keeps us from sliding our cars all over the place, and helps us go and stop. It’s also bad, because the higher the friction, the higher the fuel consumption.
How Silica Works
Don’t worry, we’re not getting this into it.
You may have heard of carbon black before. It’s the most well known tire filler and it’s responsible for making tires, well, black. It’s also what hardens the rubber compound, which is great for traction, but bad for fuel consumption. Why? Because it increases the friction which increases the rolling resistance.
However, when you combine silica with carbon black (and the other tire ingredients), some chemical magic happens. You see, silica actually decreases the rolling resistance! It does this by counteracting the hardness resulting from the carbon black, making the tire just a little bit softer.
So what does this mean for winter tires? Well, thanks to the silica, this means that the rubber in winter tires stays pliable even when the temperature drops below freezing.
Although it’s not visible to the naked eye, the surface of ice is actually not perfectly smooth, there’s tiny imperfections. The flexibility provided by the silicon means it’s better able to conform to surfaces like this, giving it some extra gripping power!
Since it improves grip (especially in rain or snow) and reduces fuel consumption, it’s also starting to be used in all-season touring tires as well. This flexibility also means it can soften the ride without degrading handling.
But silica isn’t done working its magic yet! Engineers have combined it with carbon black and other fillers to even increase the life of tires while still keeping them affordable. So your tires can last longer and perform better and not cost an arm and a leg.
So the next time you’re not slipping through a puddle or skidding in the snow, say a thanks to silica.