Tire producers work on finding more uses for nearly a billion units discarded annually after end of road wear

Tire manufacturers have intensified in recent years efforts to make their industry more sustainable by searching how to reduce waste at the end of the product’s road life, by cutting down on carbon, and in a particular case by testing a prototype of a biodegradable, no longer pneumatic but solid wheel.

Goodyear Chemical - Beaumont,Texas Image courtesy of Goodyear

Companies like Goodyear in the U.S., Bridgestone from Japan and Michelin from France, as well as Continental from Germany, have been behind some of these efforts.

Scrap tires are finding uses in areas like construction. The State of California has promoted using chipped old tires as lightweight building material in two infrastructure projects for urban transport.

“An estimated one billion tires around the world reach the end of their useful service life every year,” according to a joint statement by Michelin and Bridgestone on Nov. 17.

Carbon black

Bridgestone announced in November along with Michelin joint efforts to discuss carbon black recovery from discarded tires. The material can strengthen rubber in new tires, be used as pigment, stabilizer for ultraviolet rays, or for insulation.

“Today less than 1% of all carbon black material used globally in new tire production comes from recycled end-of-life tires due to a weak supply pipeline for the recovery and reuse,” the companies said.

Using recovered carbon black in new tire production reduces carbon dioxide emissions by up to 85% compared with virgin materials, the companies added.

Michelin runs 71 tire production facilities that together produced 170 million tires in 2020.

Goodyear’s sustainable tire for 2030 

Akron,Ohio-based Goodyear serves automotive and air travel. It also supplies polymers to diverse industries.

“We've constructed a tire without petroleum-based content and traditional fill materials like carbon black and sand based silica,” said on Nov. 5, during the third quarter 2021 earnings call, Goodyear’s CEO Richard Kramer, according to a Motley Fool transcript.

“With this momentum, we've challenged ourselves earlier this year by setting a goal of developing a 100% sustainable material and maintenance free tire by the end of this decade,” he added.

Goodyear is also cutting down on carbon. Its manufacturing facilities across Europe, Middle East and Africa will run with renewable energy by the end of 2022. Kramer estimated the shift may reduce the company’s carbon footprint “by up to a quarter of a million tons.”

Tire-derived aggregates

According to the California Department of Resources Recycling and Recovery, or CalRecycle, tire-derived aggregates made out of “shredded scrap tires” can find uses in a wide range of construction projects.

Tire-derived aggregate can help build roads, and other engineering projects where lightweight filling material may be needed. Scrap tires material can cut the need for mined resources such as gravel, according to CalRecycle.

Additional benefits for vehicles may include reduced vibration in roads.

The aim is to cut down on plastic waste. There are 40 million scrap tires per year just in California. California has been able to divert about 500,000 tires of that from reaching landfills thanks to two urban transportation infrastructure projects that used the tire aggregate lightweight material, according to CalRecycle.

Separately, the U.S. Tire Manufacturers Association (USTMA) said on Nov. 6 that the infrastructure investment and jobs legislation will “support the advancement of scrap tire markets through research on innovative pavement materials and storm water control systems.” U.S. President Joe Biden signed the law in mid-November after its approval by legislators.

Michelin’s organic tire

Michelin, one of the world’s biggest tire manufacturers along with Bridgestone, presented in June 2017, in Montreal, a prototype of an organic tire it named Vision.

The materials used for Vision were both bio-sourced and biodegradable, it said.

The tire was 3-D printable with the possibility of adjusting tread.

Michelin said on Feb. 23, 2021 that “inspired” on that Vision concept tire from 2017 it had decided to announce a corporate goal of making all tires produced by the company sustainable by 2030.

“Nearly 30% of the components used in the manufacture of tires produced by the Michelin Group are already made from natural, recycled or otherwise sustainable raw materials,” the company said.

Preventing landfill disposal

The U.S. has advanced significantly in recent decades on efforts to prevent used tires from going to landfills. One alternative developed that helped reduce landfill fillup was to burn in furnaces.

As of 2003, markets for scrap tires were consuming 233 million units per year, or 80% of the 290 million annual total tires produced at the time, according to information by the U.S. Environmental Protection Agency (EPA).

Half of those scrap tires prevented from reaching landfills in 2003 faced furnaces as they were used for heat or to replace more expensive carbon coal or wood.

In 1990 only 17% of the discarded tires found an aftermarket, either as fuel, filling material for asphalt or in civil engineering applications.  For many years before that most used tires in the U.S. were poorly disposed, and often served as breeding ground for pests, the EPA said at the time.

Continental’s Taraxagum

Another leading tire producer, Germany-based Continental, which supplies tires for a third of all new light vehicles in Europe, plans to obtain rubber from dandelion roots which grows as weed.

In 2016 it built a prototype of a tire called Taraxagum, after the plant’s botanical name. At the time, it had not envisioned commercial production using the material for at least five years.

According to Continental’s website, the company has modified the Russian dandelion, which normally grows as a flowering weed, so that the crops would yield more watery fluid to replace petrochemical-derived material.

Butadiene, polymerized, is a key intermediate for tire production and just one among many petrochemicals that support vehicle, heavy machinery and aircraft manufacturing.

Biodegradable plastic appears to have so far found more success in commercial applications that have a short life like sachet packets that hold condiments.

Petrochemicals have much higher heat resistance and can remain stable for decades.

By Renzo Pipoli