Car tires get a sustainable-materials makeover from Goodyear (photo courtesy of Goodyear).

Goodyear Cooks Up “Stone Soup” Sustainable-Materials Car Tires

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The Goodyear Tire & Rubber Company is on a mission to introduce 100% sustainable-materials car tires by 2030. To get there, the company has deployed a sort of stone soup strategy, adding new ingredients as they come along. It seems to be ahead of its own curve, with steps in place to hit the 90% mark within the next year or so. As for what it means by sustainable, that raises some good questions.

What Does Goodyear Mean By Sustainable-Materials Car Tires?

In terms of overall sustainability, cars are not the ideal place to stake a claim, at least not in relation to walking, biking, mass transportation, and the general avoidance of cars whenever possible. That goes for electric cars, too.

Cars are not going anywhere anytime soon, though, and neither are car tires. A more useful way to look at sustainability is through the lens of improvement. In that context, there is plenty of room for improving car tires.

Goodyear sets a broad but relatively clear standard for the kinds of materials that go into sustainable-materials car tires.

“A sustainable material is defined as a bio-based/renewable, recycled material or one that may be produced using or contributing to other sustainable practices for resource conservation and/or emissions reductions including mass-balance materials,” the company states.

Wait, What Is Mass Balance?

If you’re wondering what mass balance has to do with car tires, that’s a good question. In science, mass balance refers to inputs and outputs. As applied to sustainable car tires, mass balance is a chain-of-custody bookkeeping model that enables producers to claim a percentage of credit for using more sustainable materials, even if petrochemicals and other less-than-sustainable materials are still present in the supply chain in some degree. Ideally, setting a standard for disclosure will help motivate manufacturers to prod their suppliers into using more sustainable materials.

Petrochemical stakeholders that are transitioning to more sustainable materials have been advocating for a mass balance approach to sustainability reporting in their industry. That includes the global firm Borealis, for example. In an article republished by the World Economic Forum in 2022, the company’s Head of Sustainability and EU Affairs, Eugenio Longo, explained that “…mass balance is the particular model that the plastics and chemical industry sees as having the most potential in helping transition to a circular economy.”

The (More) Sustainable Tire Of The Future Is (Getting) Here

As with other forms of sustainability book-keeping, the mass balance model is open to charges of greenwashing. Goodyear, though, seems to avoid that issue by focusing on its progress towards a goal. Using the hyphenated “sustainable-materials” descriptor also helps to focus attention on the individual materials that go into car tires, of which there are many aside from rubber.

Goodyear introduced a demonstration version of its sustainable car tire last year, billing it as a “70% sustainable-material tire.” The company also clarified that the tires will have “up to 70% sustainable-material content” when they go into commercial production later this year, so it will be interesting to see how close to the 70% mark they can get on a scaled-up level.

Goodyear’s website provides a signup page for potential customers to get updates on the availability of the up-to-70% tire. They can also get a rundown of the materials that qualify for sustainability under Goodyear’s model.

In the bio-based area that includes soybean oil for traction and rice husk ash silica for fuel efficiency, Goodyear also notes that the 70% sustainable car tires incorporate carbon black for lifespan, from either plant-based sources or from waste tires.

Stepping Up To 90%, With Mass Balance

Getting to the next level will take some doing. In a press release last week, Goodyear elaborated on the ingredients that went into demonstrating its new 90% sustainable-materials car tires.

The new tires incorporate “mass balance polymers from bio- and bio-circular feedstock” certified under the International Sustainability and Carbon Certification system. As a member of the Ellen MacArthur Foundation’s CE100 Network, ISCC advocates for the mass balance approach in the chemical industry, to encourage the use of recycled materials.

“The chemical industry uses a small set of raw materials or feedstocks to produce tens of thousands of products, many of them at ‘world scale’ plants operating at very high efficiency,” ISCC explains.

“…however, the industry has been much less proficient at getting back the non-consumable products it produces once they have been used and feeding them back into production,” they add.

ISCC also points out that the mass balance approach is already used to track sustainable sourcing in various industries, though the examples they cite — the Forest Stewardship Council and the Better Cotton Initiative — also illustrate the limitations of sustainable sourcing guidelines.

New Technologies, New Opportunities For Sustainable Car Tires

In the carbon black area, the 90% tire will include sourcing from methane and carbon dioxide as well as plant-based and waste tire sources.

We’re guessing that the company is eyeballing new technology that involves capturing ambient CO2 from the air, combining it with green hydrogen to produce methane, and passing the methane to a bubble reactor containing liquid tin. The Karlsruhe Institute of Technology in Germany launched just such project in 2020. If you have another guess, drop us a note in the comment thread.

New plastic recycling technology appears to be opening up new opportunities. Goodyear mentions that the tire cords will use technical grade polyester, sourced by re-forming post-consumer plastic bottles into their chemical building blocks. That’s a significant step up from conventional plastic recycling technology based on melting or shredding.

The new tire will continue to use soybean oil, at least for the present time. That could raise some food supply issues, but according to Goodyear soybean oil is in surplus. “While nearly 100% of soy protein is used in food/animal feed applications, a significant surplus of oil is left over and available for use in industrial applications,” the company points out.

Also returning is rice husk residue, which Goodyear notes would otherwise end up being discarded.

A new addition to the Goodyear bio-based roster is pine tree resin, which will replace petroleum-derived resin. That may seem a bit futuristic, but the firm Harima Chemicals Group points out that its pine resins are already common across several industries. They list printing ink, paints, and adhesives, as well as emulsifiers for synthetic rubber, chemicals for paper production, and solder for electronics.

Rounding out the sustainable tire materials is steel for the bead wire and cords. Goodyear plans to use steel with a high-recycled content, paired with electric arc manufacturing for reduced greenhouse gas emissions.

More Headaches For Fossil Energy

While all this is going on, a dangerous blight is threatening the global supply of natural rubber. All else being equal, that would be a great opportunity for petrochemical stakeholders to increase their hold on the supply chain for car tires with synthetic substitutes.

However, as Goodyear is demonstrating, not all is equal.  Sustainable-materials car tires are part of a broader trend towards the use of recycled materials and non-petrochemical materials for various car parts. Other natural rubber substitutes are in development, with much of the attention focused on rubber derived from dandelions.

The US Department of Defense is also lending its financial firepower to push the bioeconomy along towards  a goal of replacing 95% of petrochemical feedstocks with bio-based alternatives, so stay tuned for more on that.

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Tina Casey

Tina specializes in advanced energy technology, military sustainability, emerging materials, biofuels, ESG and related policy and political matters. Views expressed are her own. Follow her on LinkedIn, Threads, or Bluesky.

Tina Casey has 3152 posts and counting. See all posts by Tina Casey