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EV Tyres: Mind the differences

As the electric vehicle segment grows, drivers need to be better educated about unique performance characteristics of tyres for these vehicles

By Louis Rumao

Tyre design and manufacturing have evolved along with automobiles over the decades and the current electric vehicle (EV) phenomenon promises to be a significant step in this evolution.

Tyre makers will swear, without exception, that their tyres are designed “ground-up.” We want to see that they are also “charged-up” when it comes to designing tyres for the expected growth in the EV segment. Puns aside, there are significant performance and operating differences between the internal combustion engine-powered (ICE) vehicles and the new EV’s.

All tyres are expected to deliver high performance and a long lifecycle. Tyres are a critical component to overall vehicle performance. Differences in torque, mass, size, and performance needs of various vehicle models affect tyre performance and longevity. Additionally, electric car design is largely geared toward extending driving range on a single charge. With over 200 variables involved in tyre design, including tread design, material selection, manufacturing process, construction, and sidewall design, optimizing tyre performance is a constant challenge to tyre companies.

Ideal environment for EV’s

“The combination of increasing regulations to reduce emissions, the desire to reduce dependence on fossil fuels, and rapid gains in battery technology is creating an ideal environment for electric vehicles,” said Chris Delaney, president of Goodyear Europe, Middle East and Africa. “We are working with automakers to introduce our Electric Drive Technology, designed to address the unique performance requirements of this growing vehicle segment.”

Anyone who drives an EV first notices how virtually silent the power-train is, which means that tyres need to be quiet since the lack of engine noise won’t cover up any road noise. Usually, minimizing tread gaps where sound waves could bounce around seems to help in reducing tyre noise. Individual block and groove sizes need to be optimized to find the perfect compromise for noise reduction.

Electric cars are heavy, typically about 20% heavier than a comparable ICE-powered vehicle; this can also accelerate wear and hurt handling. A conventional tyre can wear 30 per cent quicker on an EV than on an internal-combustion vehicle, so putting more rubber on the road with a tighter tread pattern and using a harder-wearing rubber compound helps. Tyre sidewalls need to be strengthened in order to cope with the extra vehicle weight.

Unlike in the case of ICE vehicles, in an EV maximum torque is produced from the get-go. This faster acceleration scrubs the tread and makes it wear more quickly. Therefore, EV tyres need to be more durable than the ICE vehicle tyres.

Tyres for EVs are a carefully crafted compromise for every vehicle, a compromise that emphasizes some attributes over others, because you can’t have it all. Great-handling tyres have poor durability. Durable tyres are noisy. Quiet tyres suffer from poor handling. The EV manufacturers have challenged the tyre industry to make tyres that have low rolling resistance, low noise, but can still handle the instant torque of an electric motor.

For EVs, range is also crucial, and tyres need to play their part in squeezing every mile from every watt. A “sticky” tyre would grip road better and thus better handle the instant torque of an electric motor, but will sap the car’s electric range due to high rolling resistance. Likewise, a tyre that is durable enough to handle the instant torque will likely be a loud tyre.

So, tyre 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. Tyre manufacturers strive to create customized compounds and construction that stiffens tyre without degrading comfort. Some EV tyres 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 are another important factor in the tyres’ design—down to tweaking tread patterns, block sizes, and groove widths to minimize noise. The Michelin Energy Saver A/S tyres that come standard on the all-new Chevrolet Bolt EV are custom built specifically for that car.

No doubt, tyres for EV’s are going to be different in one more key aspect: they are probably going to be more expensive!

EV tyre longevity

As EV’s continue to evolve and become more popular, it only makes sense that tyres specifically for electric vehicles will become more common and, hopefully more affordable. Drivers can help themselves by observing some common-sense practices:
Avoid jack-rabbit starts to accelerate quickly when you don’t have to, reduce the number of sharp turns, and use your regenerative breaking to your benefit.
Check the inflation pressure. Excessively low tyre pressure and heavy loads will increase the tyre’s rolling resistance and driving range. You can always keep your tyre pressure 0.2 bar above OEM’s recommendation.

Pay attention to tyre wear and rotate them as recommended by the OEM or tyre manufacturer. Rotating tyres ensures even tyre wear and maximizes service life.
For replacements, choose high quality tyres with Class A fuel efficiency. They may be more expensive, but you will get the difference back in terms of service life and energy savings.

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