Tires: Black, Round – and Increasingly Sustainable

Author: Matthias Gaul

Apr 13, 2022 Future Vehicle & Mobility Services / Sustainability / Automotive

Whether it’s because of recycled materials, retreading, or longer service life: More than ever, all signs are pointing to green in the tire industry.

Circular economy, with the goal of using raw materials as long and frequently as possible and managing natural resources in cycles as much as possible, is clearly gaining traction in the economy in view of the challenges posed by climate change. The tire industry is a good example. This is not surprising, seeing as car tires are made of more than 200 different materials. These include natural and synthetic rubber, carbon black and silica, steel and textile reinforcements, and various chemicals. When you consider that tire manufacturers sell a combined total of around 1.6 billion car tires worldwide every year, as calculated by Michelin, the potential that lies in a sustainable circular economy quickly becomes clear. Especially since a similar number of tires end up in the trash every year.
Tires made from recycled materials and renewable raw mate
As an example against this backdrop, Continental has set itself the goal of successively using 100 percent sustainably produced materials in its tire products by 2050 at the latest. On the way to achieving this goal, the company recently concluded a development agreement with German company Pyrum Innovations AG. The goal of the collaboration is to further optimize and expand the recycling of used tires through pyrolysis. One of the medium-term goals is to obtain particularly high-quality industrial carbon black in order to further increase the stability, strength, and durability of tires. The proportion of carbon black, to which tires owe their black color, is 15 to 20 percent in a standard passenger care tire. As far as sustainability is concerned, Continental already presented the “Conti GreenConcept” at the IAA Mobility 2021 in Munich with a 17 percent share of recycled materials and 35 percent share of renewable raw materials – including natural rubber from dandelions, silicate from the ashes of rice husks, as well as vegetable oils and resins.
Competitor Goodyear wants to develop a fully sustainable tire as early as 2030. In a first step, the company presented a prototype in January 2022 that consists of 70 percent sustainable materials, such as carbon black made from methane, carbon dioxide, and vegetable oils. In addition, they use soybean oil as a substitute for petroleum-based products, as well as silicate from the ashes of rice husks.
Michelin is also committed to the greatest possible sustainability and is working with French company Axens and French research institute IFP Energies Nouvelles as part of the “BioButterfly” project to produce butadiene – an important component of synthetic rubber used in tire manufacturing – on the basis of biomass from wood, rice husks, leaves, corn stalks, and other plant waste instead of petroleum. In addition, the company is implementing many other projects to regenerate PET, recycle polystyrene, or recover carbon black from used tires.
Bridgestone, in turn, has developed the “Techsyn” technology in a cooperation with Dutch company Arlanxeo and Belgian company Solvay. “Techsyn” combines chemically optimized synthetic rubber with silica that interacts on a molecular level. Particular focus was placed on improving tire wear during development, to ensure less material loss and reduce raw material consumption in the long term.
Tires with longer service life
Speaking of tire wear, Michelin specially developed a 3D printing technology that enables particularly filigree structures in the tire profile and thus makes the tire more durable. According to the company, it should be possible to drive the tires down to the legal minimum tread depth of 1.6 millimeters, and they would still have optimum braking performance.
Finally, another important strategic topic in the area of circular economy is retreading, which has been offered by specialized companies and numerous tire manufacturers for years, such as for commercial vehicle tires, motor racing, and aircraft tires. Continental, for example, is currently looking into entering the retreading of passenger car tires. In principle, retreading can significantly reduce the use of valuable resources such as crude oil, natural rubber, and water. In addition, CO2 emissions can be reduced: The production of a retreaded commercial vehicle tire requires up to 70 percent less energy than the production of a new tire.
DEKRA tests abraded new tires at the Lausitzring
Christian Koch, an expert for tires and wheels at DEKRA Automobil GmbH, feels extremely positive about manufacturers‘ efforts to achieve the greatest possible sustainability – including from a road safety perspective. In terms of tread depth or service life, it is true that the tire grip understandably decreases over time, especially on wet roads, which in turn increases the braking distance. “But we have to let go of a rigid 3- or 4-millimeter rule; manufacturers’ tires differ too much for that,” says Koch.
In this context, he is also eagerly awaiting the results of a series of tests carried out in mid-March 2022 at the DEKRA Technology Center at the Lausitzring in Brandenburg with new tires that have been abraded to two millimeters, and their behavior on dry and wet roads. As far as retreading is concerned, the DEKRA tire expert also has no reservations: “The quality of the products from renowned retreaders can definitely be compared with new tires when considering the technologies used for this purpose.”