Tire makers all in on pursuit of 100% sustainable tire

Sustainability isn't a half-way kind of effort. It's more of an all-in kind of thing. A get-it-just-right and have-the-biggest-impact sort of strategy.

For some of the world's largest tire makers, that all-encompassing focus takes shape in a goal of bringing to market a 100-percent sustainable materials tire. But the keys to developing an all-sustainable tire remain: It has to be done well, and it has to be done correctly.

"Anybody can make a 100-percent sustainable tire," Russell Shepherd, technical communications director for Michelin North America Inc., told Rubber News. "But making one with performances that are equal to or better than the current (tires)—one that people can afford—that is the real goal."

The 100-percent sustainable materials tire goal is a critical milestone along each company's sustainability journey. But it also is the embodiment of a broader effort to build environmentally friendly companies that are more sustainable in every aspect of business.

"Hankook Tire considers the topic of sustainability a genuine business philosophy," said Rob Williams, Hankook Tire America Corp.'s senior vice president of North America sales. "Behind the pursuit of a 100-percent sustainable materials tire is the core belief that our company is contributing toward improving our environment."

Michelin has articulated this same kind of focus around a simple pledge to consider people, profit and planet in every business decision, tire design and operation. And Shepherd is quick to note that this isn't new for Michelin North America or its parent company.

"That is the latest articulation of what is in Michelin's DNA," Shepherd said. "We have always tried to balance people, profit and planet."

Goodyear, likewise, considers all three of these pillars in its sustainability plan, one that Chief Sustainability Officer Ellis Jones said is woven into every aspect of the tire maker's operations—from budget planning to end-of-life tire management.

And it's the same for Continental A.G.

"We are convinced that sustainable and responsible business increases our ability to innovate and shape the future—adding value to the company and society," Claus Petschick, head of sustainability for Continental Tires, said of the tire maker's "relentless" sustainability pursuit. "… To this end, Continental sees sustainability as covering all four phases of the value chain of a tire, including material sourcing, operations, use phase and the end-of-life phase."

Short term, both Michelin and Bridgestone have articulated aims to ensure that at least 40 percent of the materials used in their tires by 2030 are sustainable and sustainably sourced.

Michelin already has made strides in pursuit of its short- and long-term goals.

As of 2021, Shepherd said, Michelin has achieved 29-percent sustainable materials usage across its entire portfolio.

"Internally, we have set targets for our products," Shepherd said. "When it comes to the next-generation product, it has a sustainable target. … And, at Michelin when we set a target, we tend to hit it. We are serious about that. When say we want to be at 40 percent by 2030, we have plans in place to get there."

That plan, Shepherd said, takes Michelin all the way from 40- to 100-percent sustainable materials by 2050. And the company, he added, is well on its way to that 100-percent sustainability mark.

Earlier this year, Michelin debuted a racing tire with 53-percent bio-based and recycled content that was used in the running of the 24 Hours of Le Mans. That, Shepherd said, was a significant achievement, and not just because of the amount of sustainable materials used in the tire. To be used in an endurance race, he said, the tires had to achieve some significant performance parameters, which this tire did.

"Racing is fun, and it is fun because it's not easy," Shepherd said. "It is not easy to make a race tire and make one that is on an electric Porsche. … (Endurance racing) is one of the most challenging environments for tires."

What is most exciting about the 53-percent sustainable materials tire, Shepherd said, is that it proved itself—and its capabilities—against some of the most stringent conditions. Racing, after all, is the proving ground for some of the tire maker's most promising technologies, including advancements in synthetic rubbers.

"(Racing) is one of the first places that we take something that we believe is ready for the market and test it," Shepherd said. "… It is a great place to quickly get results, analyze them and continue to improve."

Those racetrack successes have led to the development of a pair of road-ready tires that push the limits of the tire maker's sustainability offerings to date. On Oct. 5, Michelin rolled out a 45-percent sustainable car tire and a 58-percent sustainable bus tire. Those tires represent what Michelin believes will be the baseline for sustainability of it products in the next two to three years.

Like Michelin, Bridgestone is moving steadily forward in its pursuit of fully sustainable materials. And achieving these near- and long-term goals will take a holistic approach, according to Bill Niaura, Bridgestone Americas' director of sustainable materials and circular economy. That means bringing every facet of the business along for the sustainability ride.

Because every department—every employee—has a role to play in the pursuit of sustainable products and operations.

"We have dedicated teams across the enterprise working to deliver on our commitments," Niaura said. "This includes not only significant technical efforts, but work in product planning to identify where and how we can capture value for what will be a relatively scarce product in the near term, and with procurement to ensure that we work collaboratively with our supply base to understand supply-ability, price and timing."

In its pursuit of a 100-percent sustainable materials tire by 2050, Continental is aiming first for 60. By 2030, the tire maker looks to have at least 60-percent of the materials used in its flagship tires qualify as sustainable and sustainably sourced.

"We have a holistic approach to a gradual transition to 100-percent sustainably produced materials in our tire products by 2050 at the latest," Petschick said. "Our goal is to be the most progressive tire company in terms of environmental and social responsibility."

Goodyear, meanwhile, has established a different, more ambitious goal, targeting 2030 as the initial deadline for introducing its 100-percent sustainable materials tire—one that it envisions being nonpneumatic as well. And while that goal is a lofty one, the Akron-based company has made some significant strides toward that end.

In January, Goodyear demonstrated that it could produce a 70-percent sustainable materials tire. To do so, it leaned into recycled materials—such as recovered carbon black and polyester made from recycled plastics. It also called on bio-based materials like rice husk ash silica and soybean oil, among others.

Later, at Germany's IAA Transportation expo in September, Goodyear showed off a 60-percent sustainable demonstration truck tire.

The tire maker is proud of both achievements, Jones said, but it still has a long way to go. And the challenges, he said, are coming from a number of sides.

Because it's not just about getting the sustainable materials in the tire, it's about getting the right sustainable materials in the tire to ensure it performs as well or better than its predecessors.

"Think about the engineering of the product and the complexity that we have in our products," Jones said. "If you have three different carbon blacks in your tire, now you have to have three different sustainable carbon blacks, or you have to change to one carbon black that is sustainable."

For years, Goodyear has championed its development and use of soybean oil as a replacement for petrochemical-based oils in tire compounds. In fact, the tire maker has articulated its vision of replacing all petroleum oils in its tires by 2040.

The abundance of soybean oil, coupled with its ecological benefits—the oil is made from byproduct and doesn't compete with food sources—Goodyear believes it will play a critical role in making more sustainable, better performing tires.

"We introduced soybean oil in consumer product lines several years ago, and it was for performance. And we found out that soybean oil, when put in certain compounds, gave us better performance in the tread, more pliability in tread," Jones said. "It gives you better traction in adverse conditions. And then we said, man, this is also a sustainability benefit."

While soybean oil is prevalent in tires that Goodyear manufactures today, it remains a critical component for reaching the 100-percent sustainable tire goal.

But soybean oil, abundant in North America, isn't so abundant in Europe. So Goodyear is looking to other bio-based oils as petroleum oil replacements there. Particularly, Jones said, it has found some success with sunflower oil and Brassica napus—more commonly known as rapeseed oil. Both are widely available in Europe and could provide some of the same performance properties and sustainability benefits as soybean oil.

Sunflower oil has been one of the materials that Michelin has depended on in the development of its 47-percent and 53-percent sustainable materials racing tires. It's relied on some other organic materials as well, finding uses for orange peels and pine resins.

But there's another advancement that Shepherd is particularly proud of.

"Coming up with sustainable synthetic rubber, for me, that is the really cool thing," Shepherd said.

Michelin is tapping into technology that uses recycled styrene and bio-butadiene to create more sustainable synthetic rubber. That rubber, Shepherd said, was used in the 53-percent sustainable tire, so it's already proving that it could be a viable component for future tires.

"We are doing quite a bit of research to find solutions for not just producing tires in a conscious and sustainable fashion, but that synthetic rubber, which is typically a combination of styrene and butadiene, is sustainable," Russell said. "Now we can take waste products and turn that into bio-butadiene and recycled styrene cups—yogurt cups—and turn that into styrene for rubber."

Like others across the industry, Continental has added silicate from the ashes of rice husks and plant-based oils to its sustainable materials portfolio. But one of the company's crowning sustainable materials achievements is Cokoon, a sustainable adhesive technology.

Cokoon, Petschick said, is a "textile dip that replaces resorcinol and formaldehyde" in bonding applications between textile reinforcing materials and rubber compounds. Developed in partnership with Kordsa, the "open source" material science has been used in Continental's tire reinforcements since 2019. It will remain an important factor for the next-generation of sustainable tires.

And when it comes to recycled plastics, the German tire maker has found some success there, too.

"Continental is the first tire manufacturer who has started volume production of recycled polyester yarn, which is obtained from recycled polyethylene plastic bottles in a new process," Petschick said. "A set of standard passenger car tires uses the material from around 40 recycled PET bottles."

The recycled plastics technology, dubbed ContiRe.Tex, is used in three tire lines available in Europe—the EcoContact 6, PremiumContact6 and AllSeasonContact.

Finding the right materials is only part of the equation.

One of the greatest challenges facing tire makers in their pursuit of 100-percent sustainable materials tires is ensuring they have enough of those materials to manufacture sustainable tires in a cost-effective way.

"Identifying a technology is one thing," Shepherd said. "But scaling it? Part of making it affordable is the price of the tire at the end of the day, but also how do we do the capital investments to make sure that the proper solutions scale up?"

After all, Shepherd said, a 100-percent sustainable tire has to perform as well if not better than its predecessors, and it has to be something that consumers can afford.

Niaura believes that there is great value in a sustainable materials tire, one that consumers and customers—both fleets and OEMs—would be willing to pay for, even if it means a little more out of pocket up front.

He also believes that the value of sustainability will grow.

"Certainly, there are pockets of consumers that are prepared to pay now," Niaura said. "Longer term, should society decide to place a monetary value on sustainability and carbon, that will set a new baseline for everyone."

Jones agrees. He believes there is great value in sustainability. But ensuring the affordable availability of the sustainable materials is critical, and it's likely going to take some big investments—of both time and finances—to build the kind of supply chain needed.

"There is (a challenge in) just developing the supply base for these materials, because when you talk about scaling it," Jones said, "if you are only going to make 200,000 tires, well the cost of that is prohibitive. So how do you develop this supply chain for these materials?"

And not just develop it, but develop it in a way that doesn't put stress on the industry overall or any adjacent industries that may rely on some of those renewable resources. For example, the cost of a sustainable bio-based, renewable material can't come at the cost of competing with food sources.

Because it's not just about building supply chains for sustainable materials. It's about ensuring those supply chains—and the suppliers—are meeting the tire makers own standards for sustainability.

"We understand that it's not enough to just say a company is rooted in purpose and values—those values must be embedded in the full value chain," Hankook's Williams said. "It means that consumers care where the raw materials come from and how products are made."

According to Jones, that means setting the bar high for suppliers and working hard to be sure they are meeting those expectations in every aspect of their business—from ensuring human rights to reducing carbon emissions in their operations.

Because when Goodyear's 100-percent sustainable tire hits the market, it has to be exactly what the tire maker says it is.

"The goal would be 100-percent (transparency)," Jones said, "but you have to think about where are the critical materials that we go after? Our supplier code of conduct lays out those requirements. We talk about the type of labor, we address human rights there, and then we do audit suppliers to ensure they are following our supplier code of conduct."

Because to be 100-percent sustainable, Jones said, you have to go all-in.

"When you say it—language matters," Jones said. "If you say it, you have to prove it."