Heavier because of the weight of the batteries, more keen on acceleration and, above all, handicapped by the question of autonomy: the electric car is forcing tire manufacturers to reinvent themselves to meet its specific characteristics. The giants of the sector, the French Michelin, the Japanese Bridgestone, the American Goodyear and the German Continental are battling to establish themselves in a market that is both very profitable and growing exponentially.
This spring, Michelin has pushed a cocorico by presenting its new e-Primacy range, “Champion of its category in rolling resistance”! With a tempting argument: this new tire increases the range of electric cars by 7%. “Sixty additional kilometers is very important”, notes Cyrille Roget, Michelin’s director of scientific communication.
Visionary Michelin
Rolling resistance? This is the ultimate criterion when it comes to energy savings. “When the tire rotates, the part that is in contact with the ground is deformed, explains Mr. Roget. You have to imagine that it is a rounded beam that will have to flatten. This requires a significant effort which consumes energy. ” According to the Clermont-Ferrand manufacturer, this represents about 20% of the energy used by a vehicle. We measure the stake of the reduction in rolling resistance in terms of range. On this point, François Michelin had been a visionary. In the early 1990s, against the advice of some, he gave the green light to the introduction of silica in gum mixtures. The starting point for significant progress. “For thirty years, rolling resistance has halved”, says Roget.
“We estimate that by 2030, the share of electric vehicles in manufacturers’ sales will reach 50%” Cyrille Roget, director of scientific communication at Michelin
Reducing rolling resistance amounts to solving the squaring of the tire: how to avoid degrading the other qualities of the tire, in particular road holding and wear resistance? Especially since the constraints imposed by the electric car are important. “Batteries increase the weight of vehicles by 10% to 15%, recalls Mr. Roget. Electric motors also have instantaneous torque which allows maximum power to be reached from the first turns of the wheel. All this leads to significant wear phenomena which can reduce the life of a tire by 20%. ” Not to mention that the strong acceleration of the electric car can cause handling problems.
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