Continental is looking at trash heaps and recycling bins to find sustainable materials for future tires.
The company hopes to make all of its tires entirely from sustainable materials by 2050 at the latest, up from 15% to 20% renewable or recycled content today. In a press release, Continental explained how it's looking at agricultural waste like rice husks and dandelions, as well as recycled plastic bottles, to help achieve that goal.
A passenger car tire can be composed of up to 100 different materials, according to Continental, and one of the most important is natural rubber, which the company said accounts for 10% to 40% of the weight of a modern tire.
Sustainable materials in Continental tires
Tire manufacturers are looking for alternative sources of natural rubber that can be more sustainably grown on an industrial scale, as Bridgestone has done by using a desert shrub called guayule in some racing tires. Continental aims to use specially cultivated dandelions as a source of natural rubber.
Continental is also developing silica tire fillers made from the ash of rice husks, waste material that can't be used for food or animal feed, the company noted. The process of turning them into silica is also more energy efficient than conventional production processes, Continental claims.
Other tire fillers are currently made from crude oil, but Continental believes plant-based rapeseed oils and resins made from the leftovers of paper and wood processing could serve as substitutes. As with rice husks, these are waste materials that have no other practical use, the company said.
Pyrolysis process used to extract recyclable material from Continental tires
Carbon black is another major ingredient, and in this case Continental wants to recycle old tires to recover the material. It recently signed an agreement with Pyrum Innovations to use the latter's pyrolysis process, which involves using high heat to break down old tires to extract usable material. Continental is also using "mechanical processing" to separate out other materials, including rubber, steel, and textile, from old tires.
Another recycled material Continental wants to make use of is PET plastic from drink bottles, which can be made into polyester yarn for tire casings. Between nine and 15 bottles can go into each tire, depending on tire size, according to Continental.
Other tire manufacturers are also looking to make their products more environmentally friendly. Goodyear in January showed a prototype tire containing 90% sustainable materials, and plans to start making tires with 70% sustainable materials this year. Michelin and Hyundai have also partnered on sustainable materials for future EV tires.