Rubber meets the road: Inside EV tyre tech

TYRE technology is evolving at a rate of watts as vehicle and tyre manufacturers work together to meet the performance, wear and range requirements – not to mention the additional weight – of battery electric vehicles (BEV). 

For BEV owners – whether running them privately or as part of a fleet – these unique characteristics are making it more important than ever to choose carefully when it comes time to replace rubber. 

GoAuto approached tyre brands including Bridgestone, Continental and Dunlop for comment on this topic but it was Pirelli Tyres Australia technical manager Simon Pool who was willing to go on record about what goes into designing OEM-backed BEV tyres. 

Pirelli produces tyres that are fitted on the BEV production lines of Audi, Hyundai, Lucid, Mercedes-Benz, Polestar, Porsche, Rivian and Tesla but Mr Pool was quick to point out that all major tyre manufacturers are “all doing similar things”.

“It is not just Pirelli, but BEVs have completely changed the game,” he emphasised.

Mr Pool explained that the effect of rolling resistance on battery range and noise are primary characteristics for BEV tyre design, with both arguably more important than performance and wear in the eyes of manufacturers and vehicle owners.

“BEV tyres are designed to be quiet, so all you will hear inside the car are road and wind noise,” he explained, adding that many of Pirelli’s BEV-specific products incorporate sound-absorbing sponge beneath the tread.

“We’re not the only ones and most of us are now doing it, because it lessens the drumming effect, especially on SUVs, that comes up the suspension tower,” he said.

Although many car owners may opt for cheaper tyres when replacements are required, with a BEV they could live to regret the decision due to additional noise and the risk of reducing battery range by up to 50 kilometres – costing them in the long run. 

“Tyre dealers tell us about how car owners are buying a vehicle outside of their normal price range, but when they go to buy the OE replacement tyre it’s more expensive than a normal tyre; it’s a special tyre, but they don’t want to spend the money,” said Mr Pool. 

“So tyre dealers then pull the equivalent sized tyres off the shelf and put them on. Well, a month later the owner is complaining that, ‘I used to be able to get 320 kilometres and now I can only get 270 kilometres, and it’s so noisy’. 

“This isn’t just happening with Pirelli, all of us in the industry talk about this issue because we’ve all got it.”

Until comparative alternatives which meet or exceed the requirements of a vehicle manufacturer enter the market, the solution is to stick with like-for-like replacements.

“The most important message we give car owners right now is to go for ‘the perfect fit’,” said Mr Pool. 

“This means to fit the identical tyre onto the car that was developed specifically for the car, especially in the first three to four years of age.”

Alongside the constant push for less noise, less rolling resistance and a move away from oil-based compounds in favour of recycled products, all areas of focus being met by manufacturers, Pirelli has responded to one very specific industry issue that has so far remained unsolved.

“One of the strange requests we kept getting is people get a puncture with a BEV and they have to stop,” said Mr Pool. 

 “You have Tesla owners trying to put spares on the cars, which they can't, then you get them putting runflat tyres on Tesla wheels, which affects the battery life significantly because run flats are like 30 per cent heavier.

“Then they get a puncture  and the runflats don't work because they need a different wheel!”

So widespread was this issue that it prompted Pirelli to start developing semi-runflat tyres that can be fitted to a standard Tesla wheel.

“We have that new tyre coming, the semi-runflat tyre, which they are developing to try and run on the regular Tesla wheel. They’re trying to solve this problem without extra weight too, because weight on a BEV affects battery life.”

The average BEV produces more torque than a supercar did a decade ago and given the most popular model Down Under, the Tesla Model Y, develops as much as 690Nm, there is no denying tyres are put to the test now more than ever. 

Even the second-best seller, the BYD Atto 3 – a budget-friendly and relatively low-powered option – makes 310Nm, which until recently was in hot hatch territory.

These meaty torque outputs are produced from zero RPM, putting a particularly torturous strain on the tyres, especially when coupled with hard launches and the confidence immediate response gives drivers to pull swiftly from junctions into traffic gaps.

“The original BEV owner was very green and was doing it for the right reasons, but we have so many now that use them as a rocket ship and they don't care about the environment or anything,” said Mr Pool. 

Striking the balance between grip, wear, noise and rolling resistance is a delicate dance, Mr Pool explained, with Pirelli placing driving range high on the agenda. 

“The grip you get on the road comes from tyre wear, so everything we do is a trade-off. We fix one area of performance and we’re going to lose it somewhere else and when we talk about high grip, the tyre has to match the capability of the car,” said Mr Pool.

He added that electronic safety aid calibration was another reason to go for original equipment tyre replacement early in a vehicle’s model lifecycle.

“Tyres and cars are developed together, so fitting a different tyre will change the way the ABS and ESP control systems of the car react with the tyres,” he said.

Highlighting the effect of weight on the performance of BEV tyres – particularly in high-performance applications – Mr Pool gave the example of a professional driver who literally came unstuck at Bathurst.

“At the Bathurst 12-hour race for example, Audi had their electric car there and the German driver got in and on his first lap, at the first corner, he was into the sand. 

“They’re just so heavy trying to turn in, and we do want grip but we are also trying to get mileage. The first priority is safety and then it’s mileage.”