Energy
Friday, August 12th, 2022 7:35 am EDT
Russell Shepherd is the technical communications director for passenger car tires at Michelin, where he has spent 20 years working on research and development for the French tire manufacturer. He tells Canary Media that electric cars put different kinds of stress on tires, which means drivers should take those factors into account when they choose and care for their tires.
Shepherd says his company’s internal studies have found that consumers may not be aware of the ways that EVs affect tire performance. He recommends that people spend more time asking about the tires that come standard on any electric car they are considering buying. “When you’re in a vehicle, the only thing between you and the road are your tires,” said Shepherd, who is based in Greenville, SC.
Michelin produces tires specifically designed for electric cars and it says 8 out of 10 major automakers put Michelin tires on their EVs for the US market. Other legacy tire makers such as Bridgestone, Goodyear, and Perelli also offer tires that are optimized for EVs.
In theory, electric car manufacturers are already optimizing for these conditions with the tires they sell on new vehicles, but it’s always worth checking to make sure. As used EVs proliferate (perhaps with the help of a new tax credit), more drivers will have to decide which tires to buy without an automaker to guide them. Shepherd says there are several things EV drivers should be aware of when it comes to tire selection and care.
Electric Cars Weigh More
Conventional cars have heavy internal combustion engines, but electric cars are heavier than equivalent ICE cars thanks to their battery packs. An EV will put about 20% more weight on its tires than the equivalent gas-powered vehicle. “It’s not the tire that holds up the car, it’s the air,” Shepherd says. “EVs tend to have higher air pressure” in their tires.
New EV drivers should familiarize themselves with the recommended tire pressure, which may be different from what they are used to. Drivers should make it a point to check the pressure in their tires more frequently (many new cars come with tire pressure monitoring systems that do that for us.)
Efficiency Matters
The efficiency of a tire affects overall performance more with an electric drivetrain than with a gasoline-powered car. In tire engineering terms, the important metric is rolling resistance — the measure of how much energy a tire consumes in the process of rotating. Casual drivers seldom think about minimizing rolling resistance, though fleet managers do because even a tenth of a mile a gallon difference is significant over millions of miles.
Rolling resistance makes a more tangible difference in EV performance because the vehicles are so much more efficient than cars with infernal combustion engines. Tires use about 5% of the available energy in a conventional car, but 16% of the energy available in electric cars. “The type of tire that you pick has an impact on the range of your electric vehicle,” Shepherd says. Tire companies like Michelin and Goodyear are putting a lot of R&D effort into minimizing resistance while maintaining traction and durability.
Tires For Electric Cars Wear Faster
Electric cars put more torque loads on tires than equivalent gasoline-powered cars for two reasons. First, electric motors make their maximum torque at zero rpm, so when the driver pushes down on the exhilerator, the car leaps ahead. That’s one of the the things people like about electric cars, but it puts stress on the tires. EVs also exert torque in reverse through regenerative braking — the feature that converts kinetic energy back into electricity to be stored in the battery when the car slows down.
Any type of braking applies torque on the tires, Shepherd says, but EVs do more of it. They skip the coasting period between acceleration and braking, jumping straight from propulsion to regenerative braking. “That additional braking does contribute to the faster wear of the tires,” Shepherd said.
This leaves an EV driver with two options: expect to replace the tires on an EV more frequently than they are used to or invest in tires that wear more slowly.
The Takeaway
Car owners can’t do much to alter the performance of their vehicles, but fitting different wheels or tires is always an option. Most of us (myself included) allow ourselves to be seduced by promises of better handling, better wet weather performance, or faster acceleration. There are also those who like the look of 24″ wheels and tires with short sidewalls. If your objective is to get style points from your peeps, go ahead. Knock yourself out. But be aware — larger wheels and tires can slice a big chunk off your available range.
I did find one review on the Michelin site by someone who bought a set of 19″ Pilot Sport EV tires to replace the tires that came on his Model Y. He gave them 3 stars and complained bitterly that the range with the Michelins was the same as with the original tires. Really? Did he think new tires would suddenly improve his range by 40 or 50 miles? Judging by stories I have read online, he’s fortunate his range didn’t drop by 40 or 50 miles. Many EV drivers have reported a big change when they got new sneakers for the all electric chariot and seldom were they favorable. Some people are never satisfied.
As Motor Trend points out, “Tires that were originally equipped on your electric car were very likely developed for use on that car. Accordingly, the tire’s characteristics such as noise profile, longevity, grip, and rolling resistance are sometimes optimized to that specific vehicle’s traits.”
If you have had your electric car long enough to replace the tires, please share your experience with us. Did you go with the same tires your car came with from the factory or did you choose a different brand/size? How did your new tires compare to the original tires? Were they better or worse and why? If we get enough responses, we will collate them and use the data to create an update to this story in the future.
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