Winter is upon us, and with that, the need to drive your EV through anything that winter weather can dish out. Much has been written about EV range in cold conditions, but we’ve got a more practical concern: getting the right winter tires on your EV.
Most EV-oriented tires are made with two priorities: to reduce rolling resistance that robs you of range, and to carry the increased weight of an EV. Luckily, those two priorities aren’t at odds. To accommodate greater weight, tires designed for EVs have stiffer sidewalls and this also helps decrease rolling resistance. A secondary concern is road noise. With no engine noise to speak of, road noise becomes much more apparent in an EV. However, winter performance on snow and ice is not typically great on all-season or summer-oriented EV tires.
We reached out to Nokian, one of the world’s premier manufacturers of winter tires, to learn more about what the tire industry is doing for EV winter tires. Based in Finland, Nokian knows a thing or two about ice and snow.
In a traditional winter tire, the tread and sidewalls tend to be softer, since cold will harden vulcanized tire compounds. Also, winter tires are designed to conform to the road surface to help provide traction. Winter tires designed for EVs have to bridge that gap.
“High-quality materials and innovative design help bring both winter grip and good rolling resistance,” said Nokian Tyres Director of Products Steve Bourassa. “Often in our products, the base compound materials beneath the tread have a significant impact on improving rolling resistance by stiffening the rubber found behind the useable tread.”
“There’s a golden triangle of tire manufacturing,” adds Wes Boling Senior Communications and Content Manager for Nokian. “You have durability, you have responsiveness to the road, and you have resistance. And at any given time, you can really only serve two of those three masters. By durability, I mean tread life. With a winter tire, we are willing and able to sacrifice a bit of that tread life to make sure we’re able to have the responsiveness to the road and the low rolling resistance. We are able to imbue that tire with the internal core strength to help it stand up to that weight and torque without sacrificing responsiveness to the road.”
The Nokian way is to make a winter tire with stiff sidewalls using an Aramid/Kevlar belt construction, and then include a layer of foam to insulate the car from road noise, and finally a comparatively soft tread face to provide traction on ice and snow.
“Aramid is a lightweight fiber so you’re not weighing down the tire,” Boling explained. “It’s not dragging down that rolling resistance. It enables you to stay flexible and lighter while still giving you the toughness that you need. Then we put an acoustic foam between the tire and the rim in our EV-dedicated tires. We don’t do that for our normal winter tires. The idea is that foam is going to eat up the road noise at the frequencies that are most bothersome to drivers.”
