Sustainability, challenges: 5 ways tire makers are reinventing the wheel

ATLANTA—It appears there is good reason to reinvent the wheel, considering that the viability of the tire industry depends on technology and sustainability advancements.

But as the world grows more connected, it grows exponentially more complex.

Advancements in material development and innovations in tire recycling are inextricably connected today.

A tire's ingredients must be compatible with all points in its life cycle—from the compounding itself to the ability of that tire to be broken down for new life in other tires and rubber products.

EVs are shaping the future of tire manufacturing and, equally, influencing recycling initiatives.

"Our vision for tire recycling remains clear: That all end-of-life tires enter sustainable and circular markets," said Anne Forristall Luke, president and CEO of the U.S. Tire Manufacturers Association, in her May 16 opening remarks at the 9th Tire Recycling Conference, "Growing Sustainable and Circular Markets."

Here are five key takeaways from an opening panel on "Reinventing the Wheel," which featured Ian Coke, chief technical officer with Pirelli; Russell Shepherd, director of technical communications with Michelin North America; and Marcela Castano, senior materials scientist with Bridgestone.

Today's tire is a technical piece of equipment, and the onset of EVs and sustainability challenges will only make them more complex.

"Tires are an extremely technical, complex item in terms of materials and technology and the research that goes into that," Coke told the audience. "It is the only portion of a vehicle to make contact with the road.

"And it is getting harder (to develop) now with the electric vehicle."

Specifically, the requirements for tires are getting "greater and greater," Coke said, including their use on the heavier and higher torque EVs.

"But our biggest challenge as we are trying to do more—and we need to do more—is with sustainability," Coke said. "The technologies that are on the road today—and there are more and more of these technologies out there—used to be very niche.

"Now there are noise-canceling systems, run-flat mobility systems, and these technologies require new compounds and different types of structures. To get the most out of EVs in terms of range and performance, this requires new compounds and structures for rigidity."

Connectivity is another trend that will make tire making more challenging.

"All of these things are real—the material challenges as well, whether bio-based or recycled content is used," Coke said. "The best tire we have right now is 55-percent recycled content, up from 30 percent a year ago.

"And by 2040 our goal is to offer a 100-percent sustainable tire."

The tire of the future will not use 100-percent recycled content, nor 100-percent renewable content—rather, the tire of the future will be a combination of both, according to Bridgestone's Castano, who is based at the Bridgestone Americas Technology Center in Akron.

"Tires should be safe, first and foremost," she said. "We are looking at, for instance, reducing the rolling resistance of tires, and everything is done in the framework and in light of technological innovations.

"And increasing recycled content and renewable materials in tires should also take into account the entire life cycle assessment of these materials and their CO2 impact."

As Castano explains, there are two main components to tire technology development: structural and material innovation.

"For instance, we are looking at a silicone-based sealant technology, but in doing so we need to make sure you can repair the tire, yes. But then there is a recyclability component to these new technologies," she said. "So what is next? What is the future for tires? I believe the future is in the material portion, and the recyclability and sustainability of these materials."

According to Michelin's Shepherd, attendees of the 9th Tire Recycling Conference were not at a scrap tire conference.

"It dawned on me that I am at a Tire Recycling Conference, not a conference on scrap tires," he said. "And there is a major difference there, and this idea is driving a number of things in our industry."

Three major trends have emerged, Shepherd noted, from sustainability; to manufacturing a tire "with the same or better performance;" and finally, to customer (and tire manufacturer) affordability.

On the performance side, tires will play a major role in the range of an EV.

"Tires have an important role to play here," Shepherd said. "They can affect range up to 15 percent."

Road noise is a big deal in a car without an internal combustion engine, and integrating foams into EV tires has become an innovative avenue to reducing noise.

"But as we go toward tire recyclability, these things can pose a challenge to many of you in this room," Shepherd said. "What may not be as big a deal is the torque, but that is something everyone up here is working on as well."

Michelin maintains a philosophy that if a certain, more sustainable tire technology is good for an EV, it is good for any tire Michelin makes.

"The cool thing is our goals—the things we need to do to improve electric vehicles—coincide in many different ways," Shepherd said. "A more sustainable tire is a tire that lasts longer.

"And those technologies that help a tire last longer, we are putting in all vehicle tires—EVs or not. The longer we can put (tires) on the road, the more sustainable they are, and the better for all of us."

Giving tires a longer life is not simply a function of adding more rubber.

"We want to use technologies that allow us to get equal or more life with the same amount of tread," he said.

One final trend that has emerged in addressing the often inverse relationship of sustainability and performance is the Internet of Things.

"And we are starting to do this more and more in tires ... at Michelin IoT is quite prevalent," Shepherd said. "It is deployed in all of our truck tires, and we are looking at employing it in passenger tires."

Rice husk silica, guayule, dandelions, bio-based synthetic rubbers and recovered carbon black from tire pyrolysis all will play roles in the sustainable tire of the future, according to the three panelists.

"Today there is a heavy reliability on petroleum-based content, and there is a transition toward sustainable content," Castano said. "But it will be renewable and it will be recycled—there will not be a tire with 100-percent of either. All will play a role, including new sources for natural rubber."

And many of these raw materials will have different performance parameters.

"So I will need to adjust my compounding to ensure that the performance is met," she said.

Sustainability also is about the entire life cycle of the raw material.

"What energy is necessary to recover that material again?" Castano asked the audience. "And this is not just our industry—the packaging industry, every industry has similar sustainability goals ... and these will be competing goals."

Shepherd added that NR farm sustainability also is critical.

"The good news is that NR is a major component of a tire, and it already is a sustainable material," he said. "We just need to make sure it is grown and harvested in a sustainable environment."

He said that Michelin also incorporates recycled steel back into its tires, and is investing in research to use plastic from water bottles to make textile reinforcements.

Recovered carbon black, although a promising avenue to replace virgin black in tires, has not scaled up as an industry yet to be commercially viable.

And while silica is ubiquitous in terms of the amount of sand that exists, sand cannot be renewed or regenerated—at least at a time scale that is not glacial.

"So Michilen is working on rice husk silica—a byproduct of rice," Shepherd said. "We don't want to infringe on the food supply, either."

Coke noted that being socially responsible in sourcing any raw material is an important factor.

But finding new sources—and the research and development that goes into the search—requires major investments.

"It takes time and it takes money," he said. "Using sustainable and bio-based material is not cheap. Changing formulations in things like carbon black is expensive.

"And we need to think about how we can make these things cheaper."

Shepherd said that making tires last longer is one solution.

"But not last too long," Coke said to laughter. "But is there a need for accelerating material development and diversifying our supply base? Yes."

Castano noted that price point is going to be a difficult challenge, as is procuring uniform materials from all geographic areas of the world—and that is not likely to be the case with more sustainable raw materials, at least immediately.

"All industries are trying to replace fossil-based materials with recycled or renewed materials," she said. "And the same or better performance is required. And we want it recycled. And, oh yes, we want it all at a lower price.

"All of these solutions have to be complementary, and it is the reason why collaboration in all of this is critical. How can we draw this road map together?"

Shepherd added that, unfortunately, the challenges may be even more complex than Castano's characterization.

"The problem is even more complicated than that," he said. "The solutions needed for tomorrow do not exist today. The problem is identifying the sources that will make us stronger—and how those companies can be viable from startup to being a commercialized company.

"How do we make them strong enough to supply the tire industry and the world?"