Suitable tires for battery powered vehicles
EV tires special
Electric mobility needs the right kind of "shoes": the development and spread of hybrid and electric vehicles comes with an increasingly wide range of tires designed to ensure efficiency, safety and durability even with alternative power
Italy is “no country for old... engines”. Or rather: Italians are increasingly attracted by new alternative power units. Even if, in absolute terms, numbers are still small, electric vehicles in their various forms are increasing at a steady pace, nibbling away at the market share of the more traditional ICE units.
The figures related to 2020 registrations speak clearly: despite the catastrophic final balance at the end of the year with 1,381,496 registrations, down about 27% compared to 2019, EVs and hybrid sales performance stand out. Of course, on the one hand, the Coronavirus pandemic crushed the overall consumption curve and shattered early-year estimates. On the other, National scrappage measures, proposed in the second half of the year, favoured mainly alternative energy and fuels.
Thanks to government incentives, in fact, registrations of hybrid HEV cars increased by 102% in 2020 and market share tripled from 5.7% to an impressive 16.1%. Benefiting from the Ecobonus first and the Superbonus in the second half of the year, sales of plug-in hybrids and electric cars (ECVs) increased by 320% and 204% respectively compared to the previous year. Overall, "plug-in" cars recorded +250% in sales and market share increased from an almost insignificant 0.9% in 2019 to a shy but already significant 4.3% in 2020 (Source: Unrae Book 2020. Analysis of the motor vehicle market in Italy. XXI edition).
In spite of all the problems and difficulties that still hinder the development and spread of electric vehicles - from issues related to mileage and battery disposal to the need for a widespread national recharging network -, the general interest in this innovative mobility formula is undeniable. For this reason, if until a few years ago the attention of manufacturers focused almost exclusively on the vehicle, now increasing attention is being paid to other essential components with tires under the spotlight.
Tires at the top
Electric traction is characterized by very specific features and that means that tire makers must think outside the box. The first issue to be overcome is weight: because of the battery pack, an electric vehicle can weigh up to 20% more than a traditional vehicle. The increased weight affects handling and braking. Therefore, in order to bear the extra load and still guarantee performance, road handling and, above all, consumption standards comparable to an ICE vehicle, tires for electric cars need to be sturdy and light. The apparent contradiction finds an answer in the development of solutions related to sidewall structures and compounds. Moreover, EV tires must be stiff enough to counteract the rolling resistance and thus the natural deformation of the tread, helping to save the precious (but often limited) energy available in an attempt to guarantee the best electric mileage possible. Another typical feature of electric vehicles is the high-energy efficiency made available immediately. Maximum torque is high right from a standing start. The sudden delivery of power subjects the tires to considerable stress, which must therefore be developed to withstand these extraordinary accelerations. Another factor to be taken into account is the noise produced. Electrically powered cars are “silent”, and this is one of their strong points in terms of driving comfort. It is therefore quite natural that manufacturers and consumers are keen in keeping it that way. For this reason, they are looking at special foams to be introduced in the casing that make minimize the noise produced by the tire while moving. The market is rife with components and devices able to provide an effective response to the needs of electrically powered vehicles.
Bridgestone responds to the rising needs of electric mobility with "Enliten", a technology that involves a significant reduction in the use of raw materials, which results in an average weight reduction of 10% compared to a standard premium touring car tire. In addition, rolling resistance drops by an average of 20% compared to a summer touring car tire, thus reducing fuel consumption and CO2 emissions in ICE vehicles or increasing battery life on electric vehicles. All this without compromising tire life or safety and improving vehicle handling and stability. Enliten technology is already available, for example, on the Turanza Eco tire range currently found on VW Golf 8 and the electric ID.3. Furthermore, through a collaboration with Arlanxeo and Solvay, Bridgestone has also developed Techsyn, a technology platform that will be used by the Japanese tire maker in the future in creating tires for all segments. Techsyn combines a tailor-made synthetic rubber optimized with silica to create tires with up to 30% better wear efficiency, 6% lower rolling resistance, lower fuel consumption and CO2 emissions, increased mileage, longer tire life and limited long-term raw material consumption.
EcoContact6 is the name of Continental's EV proposal. Thanks to the balance achieved between the geometry of the components, the distribution of silica and the size of the tire, EcoContact6 guarantees maximum fuel efficiency. The compound includes an optimized polymer structure with strong links between silica and polymer chains. The result is a more responsive tire that offers a good balance between flexibility and stiffness, perfectly at ease on different road conditions. The reduced friction between the road and the tread is crucial in improving rolling resistance and reducing fuel consumption. The innovative GreenChili2.0 compound adapts to the road surface, reducing deformation and heat build-up reducing fuel consumption, emissions and tread wear, increasing mileage in the process. EcoContact6 features an excellent balance between the width of the ribs and grooves, offering the best compromise between performance on dry and wet roads, which results in increased safety. Finally, thanks to the innovative asymmetric shoulder design, the tire’s footprint guarantees the best possible contact with the road.
Designed with the specific goal of minimizing rolling resistance, the Giti Synergy E2 tire is therefore particularly suitable for electric cars (and not only). Giti Synergy E2 features a narrow tread section, an element that ensures not only low rolling resistance, but also better aerodynamics and less tire deformation. Thanks to the high and narrow sidewall, the tire has a larger circumference, providing better handling and a larger footprint (+14% compared to a standard 205/55R16 tire). In addition, the Giti Synergy E2 boasts a low energy consumption compound that contributes not only to reducing rolling resistance, but also to increasing the life of the tire and improving its grip on dry and wet roads. Finally, the new tread design makes the Giti Synergy E2 particularly silent. The three wide grooves allow for easy water evacuation, while the stiff shoulder blocks improve handling in dry conditions. At the moment, Giti Synergy E2 is available in two sizes: 155/70R19 for BMW i3 and 195/55R20 for Renault Scenic.
Goodyear has taken up the challenge of developing tires capable of promoting and enhancing the electric transition with a variety of solutions over the years. The latest is EfficientGrip Performance 2. Designed for cars with 15 to 18 inch rims, Performance 2 boasts an estimated 50% longer mileage than its predecessor does. The elasticity and flexibility of the tread help reduce tire wear and the longer grooves improve water evacuation. Wide ribs in the centre of the tread provide more stiffness and stability. SoundComfort technology reduces internal vibrations and noise. Goodyear has always been associated with motor racing, often used as a test bench to improve road products as well. This is the case of the Pure ETCR championship, the first multi-brand series dedicated to full-electric touring cars, of which Goodyear is a founding partner and official supplier: on track a special version of the Eagle F1 SuperSport, a very high performance road tire, will be used. This racing tire shares the same structure of the road version, including Power Shoulder technology for better cornering performance, and High Force Construction for greater stability.
Different in form and substance, the Hankook Ventus S1 evo3 was created to equip electrically powered vehicles. The new LRR compound enables a 10% reduction in rolling resistance compared to the previous model, thus saving fuel and reducing CO2 emissions for ICEVs, and helping to increase the range of EVs. The volume and structure of the Hankook Ventus S1 evo3 have been optimized to reduce its weight. A reduction that improves handling and increases mileage efficiency. The reinforced bead along with a stiff and wide centre rib also help the tire withstand the great torque when accelerating and increased cornering stiffness typical of electric vehicles. The hybrid aramid cord prevents tire diametric elongation due to centrifugal forces minimizing tread deformation improving stability and load distribution. The tread has interlocking outer grooves for improved wet grip and prevent aquaplaning. Finally, minimizing the volume of the lateral groove reduces the noise generated by the tire enhancing the expected comfort offered by a silent electric ride.
Michelin has been on the market for some time with tailor-made solutions for electric mobility (such as the Energy E-V range of tires), and recently launched e.Primacy, the first "CO2 neutral" tire. The e.Primacy, however, was not designed to be fitted only on electric vehicles, though its characteristics make it particularly suitable. The tire is part of Michelin's long tradition in researching and developing solutions aimed at reducing rolling resistance. In this sense, e.Primacy asserts itself with values among the lowest in its category. All this translates into a saving of about 0.21 litres of fuel per 100 kilometres and a reduction in CO2 emissions estimated at 174kg for combustion vehicles. However, e.Primacy’s performance in rolling resistance goes a long way in improving the energy efficiency of an electric vehicle, increasing its mileage by as much as 7%, i.e. almost 30 km more for a vehicle with a range of 400 km, compared to other tires in the same category. The e.Primacy is available from March 1 in 56 sizes, from 15 to 20 inches. For high-performance electric vehicles, Michelin, instead, thought of a dedicated solution: Pilot Sports EV, which stems from the French company's experience in Formula E. The tire has in fact been designed to meet the specific handling and mileage requirements of electric-powered sports cars.
Safety, environmental sustainability and comfort are the main values behind Nokian Tyres' development when it comes to tires for electric or hybrid vehicles. Due to the battery pack, these vehicles are heavier and therefore require more braking space. Nokian has therefore paid particular attention to the performance of its products in terms of grip on ice and snow, as well as on wet roads. Rolling resistance is also crucial: a tire that scores low values in this sense "burns" less energy during rotation. For an electric vehicle, this translates into more mileage covered on the same charge. More generally, low rolling resistance reduces fuel consumption and CO2 emissions. A large number of Nokian Tyres products have been awarded the EU's best category (A) tire label in terms of fuel efficiency. Nokian Tyres also meet the need for driving comfort thanks to low noise levels. The Nokian range includes many winter, summer, and all-season solutions, developed and tested to fit all, or nearly all, electric cars on the market: winter tires such as Nokian Hakkapeliitta R3 (e.g. e-Golf, Mercedes Benz EQC) or Nokian WR Snowproof (e.g. BMWi3), summer tires such as Nokian Powerproof and Nokian Wetproof (e.g. Nissan Leaf, Opel Ampera-e) as well as all-season tires such as Nokian Weatherproof (e.g. Renault Zoe ZE, Tesla Model 3).
Low rolling resistance, low energy consumption and increased range in electric mode. Minimum noise to ensure driving comfort. Immediate grip to counter the effect of high torque and a structure able to support the significant weight of a battery-powered vehicle. These are the main features of Pirelli’s Elect tires. Developed by the Italian manufacturer in collaboration with leading carmakers to meet the specific requirements of electric and plug-in hybrid vehicles, Pirelli tires marked "Elect" are also available as original equipment, as in the case of the Porsche Taycan. For the special German sedan, Pirelli has specially developed a P Zero Elect tire. The development followed Pirelli's perfect fit philosophy, with compound, structure and tread pattern tailor-made to fit the Porsche Taycan’s characteristics. The Pirelli Elect range of tires also includes solutions designed to cope with winter conditions, which generally means more rain and low temperatures and even snow: Pirelli Elect technology is in fact also used on the Winter Sottozero 3, Scorpion Winter and P Zero Winter lines, the latter available for the Porsche Taycan in 19 and 20 inch sizes.
Comfortable, quiet and safe: these are the adjectives Yokohama uses to describe the Advan db V552, the new car tire designed for the expanding electric market. The new model focuses on one concept: sustainability, which means lower environmental impact, low energy consumption and little or no emission. With the Advan db V552, however, noise levels have also been greatly reduced. The tread design, in fact, reduces noise to a minimum. The tread blocks and grooves arrangement within the design not only promotes a silent ride, but also offers excellent grip both in dry and wet conditions. The unique tread design combined with a rigid, strong and yet lightweight structure also helps to counteract uneven wear. The compound of the Advan db V552 benefits from the latest construction technology developed by Yokohama Rubber's technical department, called "A.R.T." (Advanced Reaction Technology) that improves the dispersion of the components during the curing phase enhancing the compounds softness and resistance, a guarantee of safety when driving. Furthermore, also the compound used for the shoulder has been studied and improved and increase resistance.