The Obsessive, Secretive Race to Make the Perfect Tire for Electric Cars

The Chevy Bolt sits on 17-inch Michelin tires.JOSH VALCARCEL/WIRED

EVERY TIRE YOU’VE ridden on is balancing act, the triangulation of qualities that negate each other. Great-handling tires don’t last. Durable tires are loud. Quiet tires can’t handle. The rubber wrapped around the wheels on every new car is a carefully crafted compromise that favors some traits over others, because you can’t have it all.

Electric vehicles complicate things further, because they demand more of everything. They lack the roar of an engine to drown out the brain-numbing drone of rubber on asphalt, so quiet matters. Range is crucial, so the tires must play their part in pulling every mile from every watt. The torquey performance demands rubber stout enough to keep up. And electrics are expensive enough without worrying about buying them new shoes every few thousand miles.

That’s why Teslas and Chevy Bolts share track time with Corvettes and Camaros (along with Accords, Camrys, Sentras, and plenty of others) at Michelin’s R&D center near Greenville, South Carolina. Engineers and test drivers put new designs through rigorous tests on a plethora of surfaces at sprawling test track shrouded in trees to ward off Peeping Pirellis.

These engineers juggle more than 200 variables—rubber compounds, construction methods, sidewall design, belt arrangement, tread design, groove width, and so on—to find the best combination for a given manufacturer and model.

For Formula E’s race cars, Michelin specially developed the Pilot Sport EV tire.MICHELIN

For the Bolt, coming later this year, Michelin delivered what it calls its best tire ever, at least in terms of rolling resistance. That’s the tendency for a tire to deform, requiring more energy to keep it rolling. The less energy you expend there, the farther you go on a charge, making a stiffer tire optimal. The tradeoff, though, is comfort. A steel wheel, for example, offers negligible rolling resistance, but is no fun to ride on. Michelin declined to reveal exactly how good the Bolt tire’s performance is.

To get there, the engineers created a customized compound and construction that stiffens the tire without degrading comfort. The variation of the Energy Saver All-Season tires going on the Bolt also are self-sealing in the event of a puncture, eliminating the need for a spare or even an inflation kit. That saves weight, which also helps boost range. Acoustics were a factor in the tire’s design—down to tweaking tread patterns, block sizes, and groove widths to minimize noise—but it wasn’t as much of a driving concern because the car’s relatively lower speeds won’t generate quite as much noise as Tesla’s more performance- and luxury-oriented lineup.