EV tyres: does the Tesla Model X give us a glimpse of the future?
With recent legislation aiming to banish non-electric vehicles from both showrooms and city centres (starting with Oxford, which wants them gone by 2020) car manufacturers are preparing for electric power to become the mainstream. Electric propulsion has emerged by consensus as the future of driving, rather than other alternative technologies such as hydrogen fuel cells.
Tyre manufacturers such as Pirelli also need to be ready for this seismic change on the automotive landscape. However, Pirelli comments that the changes it faces aren’t as much of a quantum leap as it is for car manufacturers as the same basic principles used for developing the latest generation of energy-efficient road tyres for conventionally-powered cars still apply. In other words, it’s all about maximising efficiency by avoiding the waste of any energy. The main way in which tyres achieve this is by minimising rolling resistance: cutting down on the friction between road and tyre, so that more of the energy produced by the engine is transmitted onto the road. But there’s a problem here. The way that tyres generate grip does to some extent rely on that friction, so it’s a question of striking a delicate balance between energy preservation and mechanical adhesion. The same dilemma applies to any car, but as the whole reason for electric cars is to save energy, this item is shuffled somewhat up the agenda when it comes to tyres driven by electricity.
At present, Pirelli supplies tyres to only one fully electric vehicle, although the Italian rubber is also seen on many hybrids (including of course the latest generation of Formula 1 cars, which technically are also hybrids). But the road-going fully electric car that Pirelli now equips is at the very cutting edge of this emerging technology. And it’s profoundly significant for the future.
We’re talking about the Tesla Model X, a car that in many ways redefines what an electric vehicle should be. For a start, it’s an SUV capable of seating seven people. Not only that, but it’s also one of the fastest mass-produced electric cars in the world: accelerating to 100 km/h in about 3.4 seconds and then onwards to 250 km/h. To put that into context, it’s not so far off the performance figures of Formula 1 cars – the real difference being that you can stick your dog in the back of the Model X.
The key conundrum in designing the bespoke Pirelli Scorpion Zero tyres for the Tesla Model X was therefore to combine performance, energy efficiency and grip – three values that sit at more or less diametrically opposed ends of the spectrum. Added to that is another consideration frequently associated with electric vehicles; the extra weight that the battery pack brings. Not to mention the thumping amount of instant and linear torque that these high-performance electric power units unleash onto the road.
Because of all these complex factors, creating this tyre for Tesla was one of Pirelli’s biggest technical challenges. Following on from the Italian company’s ‘perfect fit’ philosophy, the tyres now used by the Model X as original equipment were developed specifically for this car and its unique characteristics, ensuring an ideal match. “The result is not only a truly original tyre that achieves the seemingly impossible, but also a template for the future of tyre-making for this type of vehicle,” comment Pirelli. As the technology develops, characteristics of electric vehicles will of course change. Range will improve, batteries become lighter and more efficient, and performance will increase. All this will naturally affect the tyres.
And that’s why Pirelli says its personalised ‘perfect fit’ strategy will be even more important in the electric years to come. Cars are set to evolve at the sort of pace that’s never been seen before. It’s going to be…electrifying.