Tesla's Model S Plaid has a top speed of 200 mph and can reach 60 mph in under 2 seconds.
The next GMC Hummer EV weighs over 9,000 pounds and has a top speed of 60 mph in under three seconds.
The Ford Mustang Mach-E GT's dual electric motors provide more torque than a diesel-powered Ford F-150 and can accelerate the 4,500-pound vehicle to 60 mph in 3.5 seconds.
All three EVs generate torque figures often associated with high-output diesel trucks, and they're all equipped with electric vehicle-specific tires.
Experts say that in the electric vehicle era, tires must give much more than traction and safe handling in all weather conditions. Tire manufacturers are under pressure as they battle with conflicting demands for a new generation of tires in order to assist automobiles to use energy efficiently. They need have very low rolling resistance, capable of running quietly because there is no traditional engine to disguise noises, able to bear instant, huge torque from electric motors, and being lightweight to improve range between charges. And with the employment of sensors in electric cars, tires need to be able to react faster to changes in the road surface.
Tires on vehicles with autonomous driving features will collect and send data in addition to handling greater torque and heavier loads from electric powertrains. Steve Rohweder, VP of Technology Development at Goodyear said:
“Tire intelligence coming. So, think about a tire that is sensing something and telling it to the car or telling it to you on your app. Maybe it is simple stuff, like it needs to be inflated, but maybe it is more detailed information, like the tire is worn out. Or maybe it is information about the road and the fact that the traction has gone away or something the car needs to know to operate in the safest condition.
We do a lot of work there with sensors and integration with the vehicle. As you start to move towards an autonomous vehicle, where there is not a human and a steering wheel, those systems have to handle what the human was doing before."
The French tire group, Michelin, has created the Tweel, an integrated airless tire-wheel hybrid that could one day replace the traditional rubber tire.
The Michelin Tweel
According to industry experts, the majority of today's tires aren't designed for electric vehicles. A battery pack's weight sometimes exceeds that of a traditional powertrain, and full torque is delivered to the wheels instantly, often at a much higher rate than in internal combustion engine cars.
Tires also play an important role in the overall refinement of any vehicle. Engine sounds generally conceal tire and other noises in gasoline and diesel vehicles, but with electric vehicles, the sound generated by tires on pavement is transmitted directly into the interior.
The first attempts to tackle it are low tech. Tesla's Goodyear tires include an inch of foam attached to the interior of the tire to help suppress those pesky noises. It works, but tire engineers are exploring other, more advanced options. Currently, they are using 3D manufacturing technology to design new tread patterns and with 3D printers to make tooling for tire treads saves time and money allows engineers to evaluate new designs quickly.
Japan's Bridgestone was one of the first tire makers to deliver lightweight EV-specific tires to auto makers. Volkswagen's Golf-sized ID-3 hatchback went on sale in Europe last year with the Bridgestone Turanza Eco tires fitted that reduced the weight by about 20%.
The Bridgestone Turanza Eco Tire
Dale Harrigle, Bridgestone's chief engineer said:
"Once you make a tire lighter, you can make it more fuel efficient because of the reduced amount of material involved. And that's something we're going to continue to expand."
Bridgestone are also utilizing 3D-printing technology to test new tire designs and Harrigle added:
“There are little protrusions in the groove of the tire which is designed to break up the sound waves. Those are the types of technologies that we will be bringing forward into battery-electric vehicles' tire design."
While some electric vehicles use off-the-shelf tires, designing tires for the new generation of rugged, off-road electric vehicles as well as super-high-performance sedans and crossovers is a challenge. Ford partnered with Pirelli and spent 3 years developing the tires for the Mustang Mach-E GT. They needed to design a tire that best fit the DNA of Ford's fastest electric vehicle.
Larger electric trucks, such as the GMC Hummer and Rivian's battery-powered delivery van for Amazon, are even tougher because of the added weight of the battery pack.
Rohweder from Goodyear also said:
"We are seeing higher and higher load indexes requested by [vehicle] manufacturers. They want the same functionality" as internal combustion engine vehicles. The tires also have to be super-strong to stay on the rim while taking the punishment of driving over rocks and stumps and through deep, jagged ruts.”
The real technology to watch is Michelin's Tweel. It’s an airless tire-and-wheel combination, which has gone into production for light-duty tractors, lawn equipment and off-road recreational vehicles. Poly-resin spokes are what Michelin calls a shear beam assembly, basically a mechanical spring. The one-piece Tweel bolts onto the axle. The tread is still a rubber compound.
So, we will potentially see more of the non-pneumatics that's of a plastic structure and has a tread to it. While there is still a weight penalty with a bit of a performance trade-off., the technology is coming to evolve the wheel that enhances the EV.
