Toyota explores airless tyres to build lighter electric vehicles
Tokyo: Toyota Motor Corp. is eyeing airless tyres to help reduce the weight of battery-electric and fuel-cell vehicles and boost performance, even though the technology is years away from being ready for commercial use.
The automaker is using airless tyres—featuring individual motors in each wheel—on a vehicle for the first time with its hydrogen-powered concept car, Fine-Comfort Ride, unveiled at the Tokyo Motor Show last week, chief engineer Takao Sato said in an interview. Since such tyres comprise a band of rubber encircling a plastic-aluminium hub, the premise is that they could one day compensate for the weight of the motors, he said.
Currently the concept tyres weigh about the same as their pneumatic cousins, but Sato is counting on developments in the technology that can help shave 5kg (11 pounds)—or about 30%—from each tyre’s weight by as early as 2025. Sumitomo Rubber Industries Ltd, which supplied the tyres and has been testing them on local “kei” minicars and golf carts, said other Japanese carmakers are also interested, particularly for smaller electric vehicles.
“For automakers, the attraction of airless tyres is for electrified vehicles,” Sato said. While Toyota’s Fine-Comfort Ride is the size of a crossover SUV, “these wheels could be used on any electrified vehicle,” he said.
Wako Iwamura, head of the five-year airless-tyre project at Sumitomo Rubber, said his personal target is to have a commercial product ready by 2020.
The Japanese tyremaker is actually a late entrant to the world of airless tyres, following others including Bridgestone Corp. and Michelin & Cie. Michelin’s Tweel—a portmanteau of tyre and wheel—is currently available for lawnmowers, golf carts, construction machinery, and recreational all-terrain vehicles. The technology is still unproven on passenger cars, and manufacturers will need to convince both automakers and the public that they are safe.
A lighter tyre is only one of Iwamura’s goals. The other challenge to overcome is rolling resistance, or the friction that works against the tyre when it’s in motion. He estimates it’s 10% to 20% worse than current pneumatic tyres, a level unacceptable for vehicles that need to squeeze every kilometer of driving range from their lithium-ion batteries.
Cost, however, won’t be a hurdle. Iwamura says his tyres are already comparable in price to those filled with air. Bloomberg