Hanover, Germany — The electrification of vehicles is beginning to impact on the design and production of tires, according to Bruce Lambillotte, vice president of technical consulting, at Smithers Rapra.
Due to the still limited range of battery power, EVs may need to be as much as 20% or more improved in terms of fuel economy than for today's traditional vehicles, Lambillotte said at the recent Tire Technology Expo 2019 in Hanover.
Up to now, that has typically meant higher use of silica in tread compounds to boost rolling resistance, but Lambillotte said much of the advantages have “probably already has been achieved.”
Other options, he said, could come to the fore, such as the changes to the height/mass spec ratio of the tire: "A tall tire tends to have better rolling resistance, especially if it is a narrower cross section."
Indeed, he added, at least one Tier I tire company is looking in the direction of modifying the outside dimensions of the tire to improve rolling resistance above and beyond that achieved by high-silica, low-rolling-resistance treads.
“Battery-powered EVs are extremely quiet, so that tire noise is more easily perceived and is a bigger percentage of the total sound being emanated," Lambillotte also noted.
Citing estimates that tires for battery EVs need to be as much as 30% lower in noise generation, he said the issue is driving a lot of R&D in noise cancellation technologies, particularly the use of foam materials inside the tire cavity.
Smithers Rapra forecasts that sales of EVs will reach nearly 45 million units, from fewer than 5 million new registrations worldwide in 2018.
The growth rate, it said, will pick up particularly as more public power changing stations are put into service.
Smithers Rapra predicts that new EV registrations in China will jump to about 19 million in 2028 from a couple of million in 2018.
Sales is Europe and the US will rise to about 13 million and 5 million units respectively in 2028, the firm also forecasts.