How Michelin EV Tires Use Torque To Unleash Huge EV Performance

With space balls-inspired descriptors like “crazy”, “playful” and even “plaid” being used for the most powerful EVs 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 produce abundant torque from low speeds, which is a perfect recipe for hard acceleration, provided you have the tires capable of applying it to the pavement properly.

Michelin has spent a lot 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 learn more about making a world-class EV performance tire.

Construction

First on the list of essentials for a tire that can handle the monstrous torque of a high-performance EV (or even your more mainstream EV, for that matter) is tire construction. Before you add grippy rubber or the perfect tire pressures needed to maximize grip, you need a tire designed to withstand the forces involved. To that end, Michelin uses both construction techniques and advanced materials to deliver the strongest, best performing tire carcass (essentially the spine of the tire) possible.

“In a number of our tires, which are particularly high performance but now even certified for certain electric vehicles which are not generally considered high performance, we use materials such as aramid, hybrid aramid construction,” said Steve Calder, product manager at Michelin. . Aramid is a name for flavored polyamide, better known by brand names like Kevlar or Nomex. Aramid replaces nylon in the tire carcass to provide greater strength and durability.

Find out more about MICHELIN® EV tires HERE
(THIS STORY WAS PRODUCED IN PARTNERSHIP WITH MICHELIN)

But it’s not just about the materials. To allow for high torque handling capability while balancing other desirable characteristics of passenger car tires (comfort, noise reduction, etc.), Michelin uses special techniques to apply the Aramid Hybrid Belt into the tire, with varying degrees of tension depending on where the contact area on which the belt is applied. “We use variable technique and tension, so wrapping the cable over the tire, but varying how hard you pull it,” Calder said. “This allows our tire designers to adjust the contact patch shape and stresses to a degree not previously available.”

Improved contact patch shape means the tire is closer to its optimum shape to provide grip with the ground surface, allowing the tire compound to reach its maximum potential.

Compound

With our ideal contact patch shape now in place thanks to the carefully constructed tire carcass, we can turn our attention to the compound of the tire and how that helps it harness the near-instantaneous low-end torque provided by electric motors. . But what makes good torque handling capability in a tire compound?

“As vehicles get heavier and more torque is produced,” Calder said, “generally you want a stiffer compound to be able to handle that. So we’re working on the next generation of compounds that are both stiffer for this torque capacity and also very efficient.”

But these days, and even more so in the future with electric vehicles, a single tire compound is often not enough to meet Michelin’s goals. In fact, Michelin has studied the potential use of multiple compounds in a tire’s tread, particularly at the shoulder versus the middle. Michelin also evaluated different compounds on the surface versus the inside of the tire.

The specifics of tire compound chemistry are among the best-kept corporate secrets for tire manufacturers, but it’s clear that Michelin relies not only on its experience, but also on its ability to innovate to stay up to date. the cutting edge of torque management capability, with traditional electric vehicles and performance cars and internal combustion engine (ICE) hybrids.

Regenerative braking

Another main difference between ICE vehicles and electric vehicles is the ability to use regenerative braking to recover some of the energy that would otherwise be lost as heat during a more traditional braking situation (i.e. say no EV). Unlike acceleration, or even standard braking, the challenge of torque management during regenerative braking is not the absolute force but rather the frequency at which it occurs.

“An electric vehicle [has] that combination of higher torque off the start, which honestly depends on your driving behavior – that may or may not be a factor – but there’s just more consistent braking through regenerative braking that you don’t see on [vehicles equipped with] internal combustion engines,” said Russell Shepherd, Michelin’s director of technical communications. “And that’s part of the difference we’re seeing.”

Although each EV handles regenerative braking in a slightly different way, nearly all use it quite extensively by default. This means that a traditional ICE or hybrid car can go a good distance each time the driver lifts their foot, an electric vehicle will generally start using regenerative braking as soon as the vehicle stops accelerating. This greater effective frequency of brake use means that the tires (the main component that the brakes use to help slow the car) also face greater potential wear. This is where tire composition, as mentioned above, comes into play – balancing wear, grip and efficiency.

In addition to the frequency of regenerative braking, it also matters which set of wheels an electric vehicle uses to apply its regenerative braking, and that’s not always the front axle. “The other thing is, where do you do regenerative braking?” Shepherd said. “There are vehicles where you have regenerative braking on one axle, and it’s the same axle that does a lot of the driving. So that’s part of the complexity. When we talk about the impact of the torque and electricity vehicles, it’s both Acceleration and deceleration under braking.

And after?

Michelin is working on all of the above to increase the maximum operation of EV performance tires, but it is also progressing with improved wear, efficiency and, in the near future, connectivity. While connectivity is widely seen as a boon to autonomous driving by adding tire grip and other metrics to the overall data set, it’s also an area that could yield significant performance benefits. . Features like on-the-fly temperature and real-time monitoring of contact patch behavior could unlock even more grip, and therefore allow EVs to unleash even more of that “ridiculous” torque.

Find out more about MICHELIN® EV tires HERE
(THIS STORY WAS PRODUCED IN PARTNERSHIP WITH MICHELIN)

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