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How Michelin EV Tires Wrangle Torque to Unleash Huge EV Performance
To better handle the near instant torque produced by EVs, Michelin uses advanced construction techniques, compounds, and more.
With Spaceballs-inspired descriptors like "insane," "ludicrous," and even "plaid" being used for the most powerful electric vehicles and their launch modes, it's easy to appreciate the performance side of EVs, especially if you're a fan of torque. Due to their nature, electric motors make abundant torque from low speeds, which is a perfect recipe for brutal acceleration—provided you have the tires that can properly apply it to the pavement.
Michelin has spent a great deal of time and development effort working on how its EV tires handle the near instantaneous torque emanating from electric vehicles as well as other factors unique to EV operation. We recently sat down with several Michelin experts to hear about what goes into making a world-class EV performance tire.
Construction
First on the list of core essentials for a tire capable of handling the monstrous torque of a high-performance electric vehicle (or even your more run-of-the-mill EV, for that matter) is tire construction. Before adding grabby rubber or the perfect tire pressures necessary to maximize grip, you need a tire that's built to withstand the forces involved. To that end, Michelin uses both advanced construction techniques and materials to provide the strongest, highest-performance tire carcass (essentially the backbone of the tire) possible.
"In quite a few of our tires, particularly high performance but now even tires homologated for some electric vehicles that aren't typically considered high performance, we're using material such as aramid, hybrid aramid construction," Michelin product manager Steve Calder said. Aramid is a name for aromatized polyamide, better known by brand names like Kevlar or Nomex. The Aramid replaces nylon in the tire carcass to provide greater strength and durability.
But it's not just about the materials. To enable high torque-handling capacity while also balancing in other desirable passenger car tire traits (comfort, reduced noise, etc. ), Michelin uses special techniques to apply the hybrid aramid belting within the tire, with varying degrees of tension depending on where in the contact patch the belting is applied. "We use a technique and a variable tension, so actually winding the cable across the tire, but varying how tightly you pull it," Calder said. "That allows our tire designers to be able to tune the contact patch shape and stresses to a degree that was not available before."
Improving the shape of the contact patch means the tire is closer to its optimal shape for providing grip with the ground surface, allowing the tire's compound to reach its maximum potential.
Compounding
With our ideal contact patch shape now in place thanks to the carefully constructed tire carcass, we can turn our attention to the tire's compound and how that helps it harness the close to instant-on low-end torque supplied by electric motors. But what makes for good torque-handling capacity in a tire compound?
"As vehicles get heavier and more torque is produced," Calder said, "typically you want a compound that's more rigid to be able to handle that. So we're working on the next generation of compounds that are both more rigid for that torque capability and also very efficient."
But these days, and all the more so going forward with EVs, a single tire compound often isn't enough to meet Michelin's goals. In fact, Michelin has been researching the potential use of multiple compounds in a tire's tread pattern, specifically in the shoulder versus the middle. Michelin has also been evaluating different compounds on the surface versus the interior of the tire.
The specifics of tire compound chemistry are among the most heavily guarded of corporate secrets for tire manufacturers, but it's clear Michelin is leveraging not only its experience but also its ability to innovate to stay at the forefront of torque-handling capacity, with both EVs and traditional internal combustion engine (ICE) performance cars and hybrids.
Regenerative Braking
Another main difference between ICE vehicles and EVs is the ability to use regenerative braking to recapture some of the energy that would otherwise be lost to heat during a more traditional braking (i.e., non-EV) situation. Unlike with acceleration, or even with standard braking, the challenge with handling torque during regenerative braking isn't the absolute force but rather the frequency with which it occurs.
"An electric vehicle [has] this combination of higher torque at the start, which honestly depends on your driving behavior—that may or may not be a factor—but there is just more consistent braking due to regenerative braking that you don't see on [vehicles equipped with] internal combustion engines," Michelin technical communications director Russell Shepherd said. "And that's part of the difference we're seeing."
Although every EV handles regenerative braking in a slightly different way, almost all of them use it rather extensively by default. That means where a traditional ICE or hybrid car might coast a fair distance every time the driver lifts off the gas, an EV will typically begin to use regenerative braking as soon as the vehicle is no longer accelerating. This effective greater frequency of brake use means the tires (the primary component the brakes are using to help slow the car) also face more potential wear. That's where tire compounding, as mentioned above, comes into play—balancing wear, grip, and efficiency.
On top of the frequency of regenerative braking, it also matters which set of wheels an EV uses to apply its regenerative braking—and it's not always the front axle. "The other thing is, where do you do the regenerative braking?" Shepherd said. "There are some vehicles where you've got the regenerative braking on one axle, and that's the same axle that is doing a lot of the driving. So that's some of the complexity of it. When we talk about the impact of torque and electric vehicles, it's both. Acceleration and braking deceleration."
What's Next?
Michelin is working on all of the above to increase the peak operation of EV performance tires, but it's also moving forward with improved wear, efficiency, and, in the near future, connectivity. Although connectivity is largely seen as a boon to autonomous driving by adding tire grip and other parameters to the overall dataset, it's also an area that could yield significant performance benefits. Features like on-the-fly temperature and real-time contact patch behavior monitoring might unlock even more grip—and therefore let EVs unleash even more of that "ludicrous" torque.