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Winter tires for electric cars: How do e-mobiles get through the winter?

2019-12-01T07:56:09.036Z

The range of an electric car is also dependent on the tires, which is why there are special tires for Stromer. However, there are no electric car winter tires on the market - with one exception.




If you look at current sales statistics, the winter tire seems to have had its day. While the demand for all-season tires rose significantly last year, the German Rubber Industry Association reported a decline in winter tire sales of seven percent in Germany for the past year. The trend has long dominated the tire business - but perhaps he could soon reverse and the importance of winter tires increase again. The reason: electric cars.

For e-vehicles namely, the choice of tires is not only important for safety and comfort, but it also affects the range crucially. The French tire manufacturer Michelin, for example, promises a range increase of up to six percent if an e-car is equipped with the "Energy EV" tire specially developed for Stromer. However, this is a summer tire. What not even a single tire manufacturer in Europe offers are universally applicable electric car winter tires. This is due to the special requirements that are placed on such a tire.

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E-car tires are usually very narrow and have a relatively large diameter. "Tall-and-Narrow means that in the language of tire developers," says Frank Walloch, tire developer at Continental. The reason: there is a direct technical connection between tire diameter and rolling resistance. "The larger the tire diameter, the lower the rolling resistance for the same load on the tire," says Walloch. And the lower the rolling resistance, the less energy is needed to move the tires across the road. Means: tires with low rolling resistance protect the battery and let the electric car continue driving. Although this rule also applies to diesel and gasoline, but with no drive variant, the range plays such a central role as the electric car.

The eternal target conflict: rolling resistance vs. traction

Rolling resistance, however, also means: the tire sticks well on the road. Professionals speak of traction. Good traction ensures that the tire can optimally transfer drive, steering or braking power to the road. In short, driving becomes safer. Especially in winter, when the roads can be greasy and slippery, high traction is important. Also because it is the basic condition that the assistance systems of modern cars can intervene effectively and, for example, stabilize the vehicle or bring it to a standstill in emergencies.

The art of tire manufacturers is now to achieve the right mix of low rolling resistance and sufficient traction at the same time. "Braking distance, handling and driving stability must not be neglected - we have to find the best compromise between safe stopping distances and low rolling resistance - that's the challenge," says tire developer Walloch. For e-car winter tires for the German market, manufacturers must be particularly creative. Because solutions such as in Continental's "Ice Contact 3", which is equipped with rubber-coated spikes, are indeed a hit in Norway, but prohibited in Germany - with the exception of a small area along the Austrian border.

For the BMW i3, there is an "exclusive" winter tire

An e-car winter tire must therefore be designed differently. At the same time, a highly efficient winter tire would be very desirable - but the range of electric cars due to the sensitivity of the battery is already significantly reduced anyway. At the moment, however, only one tire manufacturer has the right solution - and only one car model: The Japanese tire producer Bridgestone produces winter tires specifically for the BMW electric compact vehicle i3. The model is called "Blizzak LM500" and has, as requested by the manufacturer on a high silica content, a particularly wide tread rib and specially developed 3D washboard blades to provide the best possible traction with the lowest possible rolling resistance.

Also Continental was already very close, had developed the universal E-car tires practically already finished: The prototype "Conti e Contact" was intended for the European market and was presented already 2011 as winter and summer tires. However, the pneu never made it into the series, there was a lack of demand.

A few years later, the US tire producer Goodyear tried it. In 2018, the company presented the tire model "Efficient Grip Performance" at the Geneva Motor Show. Narrow slats in the tread should ensure that the car adheres better to the road and so the high torque of an e-car can be better transmitted. However, even this tire is not yet on the market. And although Michelin has the mentioned electric car summer tires in the range for several years - there are no plans for a special electric car winter tires at the French manufacturer.

The new e-cars are also new e-car tires

The Korean tire manufacturer Hankook, however, dares next year, punctually to the announced e-offensive of the automaker, a push on the European electric car tire market. And with summer and winter tires. With the year-round "Kinergy Allseason EV", the South Koreans in North America have for some time now had an electric car tire on the market, but this is only designed for the lower speeds that are permitted there.

Crucial is not only what the tire manufacturers offer, but especially what the manufacturers raise from the factory. For example, Volkswagen is setting factory-standard passenger car tire models for the new Stromer ID.3, the summer tires "Eco Contact 6" and the winter tires "Winter Contact TS 850 P" - both products from Continental. Tire mix and tread structure were slightly modified for the new VW, it says the tire manufacturer, also the side walls were further stiffened. The tire could carry such heavier loads, such as the battery of an electric car. "The slightly different tread structure compared to the standard 'Eco Contact 6' also ensures good mileage - defying the high driving torques of the electric vehicle," says Alessandra Ferraris of the Original Equipment Tires department at Continental.

Tires with low rolling resistance and good traction, which still allow a long range: this will continue to keep the tire manufacturers in the production of tires, especially winter tires for electric cars on the go. Especially when BMW, VW and Co. continue to wrestle for every kilometer range.

Source: spiegel

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