Low rolling resistance, high load capacity, little noise – tires for e-cars require special talents. More and more manufacturers are bringing tires onto the market that have been specially developed for electric cars. Of course, Stromer do not need any special tires, they can also be equipped with conventional wheels. Then why special tire lines? The focus here is on lower power consumption.
Tires for e-cars: lower rolling resistance means range
Electric cars should achieve the longest possible range. A low rolling resistance helps. The optimized tires therefore often have large diameters with narrow treads. The rolling resistance can also be reduced via the rubber compound or the substructure. A conventional summer tire has a rolling resistance between 7 and 9 kg / t. Eco and low-friction tires have values of 6.5 kg / t and less. What range gain is possible with this? “If the rolling resistance value is reduced by 1 kg / t, we expect a range gain of three to four percent,” says Burkhard Wies, Head of Development at Continental. For a Renault Zoe with a range of around 240 kilometers that would be around ten kilometers more, a Tesla Model S with a range of around 500 kilometers would cover around 20 kilometers more.
Robust treads against premature tire wear on the electric car
Electric cars weigh a lot and have a high torque right from the start. Both of these can mean that the tires on the e-car wear out faster than on the petrol or diesel – bad for the environment and for the driver’s wallet. However, one has to differentiate: “The faster tire wear plays a bigger role in a car that weighs more than two tons and has a high engine power than, for example, in a Renault Zoe,” explains Stefan Küster from the tire manufacturer Kumho. “In addition, the driver’s driving style is also a major factor in terms of wear and tear.” How resistant a tire is to abrasion depends to a large extent on the rubber compound used.
Electric car weight requires high tire load capacity
Electric cars weigh around 200 to 300 kilograms more than comparable combustion engines. Your tires therefore need a higher load capacity. When buying tires, therefore, pay attention to the correct load index: it is in the registration certificate Part I or can be requested from the vehicle dealer. The specified tire pressure must also be adhered to and checked regularly, as it affects the load-bearing capacity of the tire. If the pressure is only slightly too low, it also increases rolling resistance and wear!
Low tire rolling noise for more driving comfort in the electric car
Because the electric motor is quieter than a combustion engine, tire noises inside the vehicle are more noticeable in electric cars. Low-noise treads are therefore an important factor for driving comfort. Vibrations in the tire cavity, which are transmitted into the vehicle interior, play a role in the development of noise. Foam inserts on the inside of the tire tread can absorb these vibrations. Such polyurethane sponges are now used by some tire manufacturers. Pirelli calls this solution, for example, the “Noise Canceling System”, at Continental it is called “ContiSilent“.
Safety despite the low rolling resistance of e-car tires
Can a tire that is optimized for rolling resistance also be top in terms of safety? “From a technical point of view, there is a trade-off between low rolling resistance and optimal grip,” explains Burkhard Wies. “When developing tires, a good compromise has to be found between the two properties, which is very successful thanks to advances in rubber compounds.” Stefan Küster also sees it this way: “A lot has happened in rubber compounds in the last two decades. This means that it is now possible to manufacture an energy-efficient tire that also guarantees very good grip.”
When it comes to electric cars, many focus on the environmental factor. A low rolling resistance is therefore an important point. At the same time, however, tires have to ensure good grip and short braking distances – even with electric cars! However, not all tire manufacturers manage this balancing act equally well. The EU tire label provides an indication. However, the results of independent tire tests are more meaningful: Compare how the tires perform in the different categories.