The Quest for Developing the Ideal EV Tire
With billions sold annually, the competition intensifies to create the perfect electric vehicle tire—one that provides the ultimate combination of enhanced range, environmental benefits, and reduced noise. The outcomes could advantage every vehicle worldwide.
IN 1845, AT SOME POINT between creating a method for detonating explosives with electricity and the refillable fountain pen, Robert Thomson, a Scottish engineer and businessman, patented the first pneumatic tire—a remarkable innovation at the time, now a common item that has been continually evolving ever since.
Currently, in the age of electric vehicles, they are receiving more attention than ever. On one hand, although ensuring passenger safety is crucial, the appropriate tires can greatly influence efficiency—and consequently the range of your EV—yet on the other hand, they also contribute to noise and pollution.
With the conventional global tire market exceeding $200 billion and 2.5 billion tires sold annually across the globe, manufacturers are eagerly anticipating the end of purely combustion vehicles, preparing for a competition to develop the ideal mix of eco-friendly attributes, performance, and efficiency to produce the ultimate EV tire. The victor will obtain a significant reward.
Rolling Resistance or Durability?
Range optimization has been the main focus thus far. Michelin states that the efficiency gap between high-quality and low-quality tires can reach up to 7 percent. Improved tires lower rolling resistance, allowing a car to glide farther before halting. Consequently, it will require less energy to cover the same distance. A 7 percent boost in efficiency will provide an EV with that much additional range—therefore, if it could cover 300 miles with a bad tire, it will reach 321 miles with a quality one.
“Several tire elements can affect rolling resistance,” states Thomas Wanka, lead technology development engineer at Continental, a company investigating EV tire design through its partnership with the electric motorsport series Extreme E. “These consist of the rubber material and the tread.”
Producers are testing nanomaterials in their tires, including nanocarbon and nanosilica, to enhance performance, grip, and longevity. Research is being conducted on bio-based alternative materials like guayule and dandelion rubber.
You can decrease rolling resistance by lowering tread depth, but this also results in a shorter tire lifespan and higher noise levels. Continental, on the other hand, believes it has the solution. “Wanka states, ‘We have created unique soft rubber materials that enable us to lower both rolling resistance and noise simultaneously without compromising mileage.'” “The tire industry frequently claims that enhancing one aspect, like efficiency, involves compromising another, such as durability or wet traction,” states Gunnlaugur Erlendsson, CEO of Enso, a startup tire firm aimed at optimizing for electric vehicles. “However, the significant disparity in performance between premium and budget tires demonstrates that the technology is already available to enhance tires overall.” The shift to electric vehicles has intensified the need to enhance efficiency, durability, and tire pollution.
The Issue with Particulates
The issue of pollution has gained attention due to increasing worries regarding the environmental effects of transportation. Electric vehicles emit no tailpipe pollutants, but this does not imply they generate no emissions at all. Although the idea that their extra weight leads to more brake dust is a misconception (since braking in EVs usually occurs via regeneration instead of friction), tire particles from wear are a separate concern. A study conducted by Michelin suggests that, on average, electric vehicles experience 20 percent greater tire wear compared to similar internal combustion engine cars.
This information has been quickly used by those seeking to criticize EVs, arguing that electric vehicles might be more harmful to the environment than diesel cars. Michelin claims that its statistic of 20 percent increased tire wear in EVs is due to their added weight, higher motor torque, and the fact that regeneration typically lessens the duration of coasting. However, producers aim to mitigate the particles left by tires by increasing their longevity.
Durability can greatly differ among tire brands, influencing the amount of rubber they wear off during use. Michelin states that a set of four CrossClimate 2 tires loses 1.5 kilograms of material over 20,000 kilometers of use, while the industry average is 3.5 kilograms, and some of the worst brands can reach up to 8 kilograms. Michelin states that this is due to the “self-adapting technology” present in CrossClimate 2 tires, which is intended to modify according to road temperature. The company has developed a more durable compound, while the tread pattern evenly distributes pressure over the tire’s surface contact area, further minimizing wear.
Nonetheless, directly comparing pollution from tire particles to exhaust emissions from an internal combustion engine is complicated. Although 1.5 kilograms of rubber particles still sounds concerning, there is a notable distinction in particle sizes. The primary offender for public health is NOx, responsible for smaller particles in the “PM2.5” classification (indicating the particles measure 2.5 microns across). In terms of tires, merely 1 percent of particulates are under PM10 (10 microns), while 0.2 percent are PM2.5 or smaller. The majority of PM2.5 pollution in cities continues to be emitted by vehicle exhaust NOx.
Regrettably, there is limited research on the health impacts of tire particles. One of the limited thorough investigations was finalized over ten years ago, in 2012. “At that point, it had not been determined that it was the main focus,” states Gary Guthrie, senior vice president at Michelin. “The main focus was to better comprehend the behavior of particles in water and their degradation process.”
“Wanka states that research funded by the Tire Industry Project (TIP) of the World Business Council for Sustainable Development (WBCSD) has shown that tire and road wear particles (TRWP) do not threaten human health.” “Inhalation research indicates that TRWP probably presents little risk to humans via airborne exposure.”
“Tire pollution and nitrogen oxide emissions are distinct,” states Erlendsson. “NOx is a gaseous byproduct resulting from fuel combustion, whereas tire particulate matter represents a solid pollutant, similar to dust produced by wood burners.” In contrast to NOx or CO2 emissions from exhausts, there are presently no worldwide regulations in place that directly restrict tire pollution.
Are Biodegradable Tires the Solution?
Biodegradable tires appear to be a promising answer to tire pollution. Nonetheless, this concept presents certain contradictions. “Wanka states that tires are critical for safety.” “They represent the sole connection between a vehicle and the road.” Therefore, it is essential that a tire does not experience any deterioration until the end of the usage phase. For numerous tires, the lifespan may last five years or longer.
“Though the tire sector is progressively investigating bio-based materials like natural rubber, tires and the pollution they create are still not biodegradable,” Erlendsson states. A tire that decomposes while on the vehicle would not be suitable for longevity. Nonetheless, it would be advantageous if the tire particles that are released while driving could decompose in the environment, stopping them from collecting in our air, soil, and seas.”
“Our emphasis is currently on the front end instead of the back end,” states Guthrie. This signifies incorporating a greater amount of recycled materials in production, seeking a level of circularity. “We would rather be able to take the tire at the end of its lifespan and create a new one from it, as that benefits the planet even more than simply using it in flowerbeds.” In this manner, we avoid extracting raw materials from the Earth to produce the tires initially. Michelin has certainly been developing biodegradable tire materials, which could advantage the whole industry. Nevertheless, if it succeeds, it is improbable that such an innovation would be offered to other producers. “Distributing intellectual property isn’t really a facet of Michelin’s culture,” Guthrie states. “Our aim regarding the broader goal is to comply with regulations—such as grasping how TRWP decomposes within the ecosystem.” “When we believe something benefits the planet and is not overly competitive, we are inclined to share it.”
An Improved EV Tire Is a Superior Tire
The emphasis on tire efficiency has been directed at EVs, due to their requirement to maximize mileage from costly batteries in a landscape where the charging infrastructure remains insufficient. However, the advantages are not limited to electric vehicles.
“Wanka states that fundamentally, there is hardly any distinction between a standard tire and a specialized tire for electric vehicles.” “Certain vehicle models or classes tend to have particular tire specifications.” Improved service life, rolling resistance, and rolling noise have notably enhanced electric vehicles. “However, all types of vehicles—no matter their drive system—gain from the technological innovations.”
“A quality tire should function effectively no matter the type of vehicle,” states Erlendsson. The tire industry is progressively seeking to promote its products as ‘EV ready,’ yet the truth is that there is insufficient regulation and consumer knowledge for individuals to make educated choices regarding what’s optimal for their vehicles. It is understood that electric vehicles impose unique requirements on tires. However, the superior technology that is already available isn’t being implemented universally for all tires, especially in the aftermarket, which accounts for 90 percent of total sales.
Tire producers continually enhance durability, which may benefit every kind of vehicle. “Wanka claims that with the new AllSeasonContact 2, Continental has boosted mileage by 16 percent compared to the previous model, while also decreasing rolling resistance.”
The rivalry among manufacturers to enhance their tires is so intense that during motor races featuring teams with various brands, companies comb the track post-event in search of rubber pieces. They subsequently bring these to the lab for analysis, hoping to uncover the secrets of a different brand’s compound material.
Nevertheless, many significant issues related to tire sustainability arise from inadequate consumer behaviors instead of the tires themselves. Guthrie from Michelin states that numerous drivers discard their tires well before it is legally required. The main issue focuses on the safety risks associated with a tire believed to be close to the legal tread limit, including increased stopping distances on wet surfaces. The outcome is shocking, as 50 percent of tires are taken off before reaching a tread depth of 3 mm, much less the 1.6-mm legal minimum. This indicates that 400 million tires are discarded early each year.
“Erlendsson states, ‘Innovations are enhancing tires to be more efficient, long-lasting, and quieter.'” “The technology for producing superior tires is already available, yet it isn’t being implemented widely because the industry lacks the motivation to adopt it.” Other than safety, regulations up to now have not addressed tire efficiency, durability, or noise, leading only high-end or specialized manufacturers to prioritize these features. Less expensive brands focus on value instead. Regardless of whether EVs will lead in vehicle types in the coming years, prioritizing the development of improved tires could be advantageous for all vehicle categories. “If you can extend the lifespan of a tire, it would also last longer when placed on a combustion vehicle,” Guthrie states.
