[Translate to English:] Foto: Imthaz Ahamed on Unsplash

Re-inventing the wheel

Tires are all-rounders. They not only put the engine's power on the road, defy centrifugal forces and bad weather conditions, but also inform drivers and workshops today about tread depth, fill level and material condition via RFID and telematics. Researchers and engineers from renowned tire manufacturers are already working hard on the next generation.

Electrified wheels

What will the tires of the future look like? The major manufacturers have very clear concepts in mind: the next generation will be greener, smarter and more flexible. Bridgestone, for example, wants to help electromobility on its feet with the "Enliten" lightweight construction technology. The more lighter an electric vehicle is, the bigger the battery can be and the further it can go with a single charge. Thanks to a patented new rubber compound and new construction, the tire type is on average ten percent lighter and reduces rolling resistance, which increases the range of electric vehicles. Sustainability is also a feature of Konzeptreifen „BH03“ von Goodyear concept tire that is designed to generate electricity. The prototypes are equipped with piezoelectric and thermoelectric generators below the surface. The thermoelectric materials convert heat into electricity, for example when the road surface has been warmed by the sun. Thanks to the thermoelectric effect, the tire can even generate electricity when stationary. The tire also warms up when the vehicle is in motion because the road surface exerts pressure on the tires. The piezo generators convert mechanical energy into electric energy, but this is possible only while the electric car is in motion. The electricity thus generated could feed directly into the on-board batteries. However, at present Goodyear has no plans to put the BH03 into series production.

Foto: Michelin
Without air and with recyclable materials – this is what the tire of the future may look like. Foto: Michelin

Revolution without air

Next to solutions for electromobility, the industry is eager to achieve airless tire concepts. In 2017 the French producer Michelin presented its „Concept Vision“ at the IAA. Its message was that the tires of the future would do without a tire pressure. Incidentally, it was the Michelin-brothers who presented the first pneumatic tires to the public at the end of the 19th century. The new tires from Michelin have an alveolar interior structure. Close to the center, the chambers become progressively smaller to provide a high level of rigidity. Towards the running surface they become larger, which makes the material flexible and thus improves suspension comfort. This architecture renders tire pumps superfluous. The innovative tires can be 3D-printed, which saves on materials, weight and costs. They are also smart – due to embedded sensors – and can accurately analyze parameters such as the road conditions and tread.

And the Vision is becoming reality. In partnership with General Motors, this June Michelin revealed the successor prototype, called "Uptis" – the “Unique Punctureproof Tire System.” It is already being trialed, and real-world testing in the US is scheduled for this year. Market launch is planned for 2024. The wheel-tire combination now presented consists of an aluminum hub, composite materials and a rubber outer surface. The hub is mated with the contact surface of the tire. The spokes are made of resin-impregnated fiberglass, providing high load-bearing capacity. Michelin points out that as the Uptis no longer relies on air pressure, it is not susceptible to punctures or blowouts like conventional tires, and requires practically zero maintenance. So the new tire not only scores on safety, but is also better for the environment.

From rubber trees to dandelions!

Tire disposal is not exactly good for the environment. Old tires are shredded and dumped or incinerated. Only a fraction of them are re-used. And there’s another problem: the supply of natural rubber is at risk. The tire industry uses 75 percent of global production. In Brazil, where rubber originated, a fungus is currently destroying whole plantations. If the fungus spreads to Asia, with its important cultivation areas, it will jeopardize world rubber production. For several years Continental has been researching sustainable tires in collaboration with scientists from the Fraunhofer Institute for Molecular Biology and Applied Ecology in Münster and other project partners. In Asia in particular, ever larger areas of rainforest have to be cleared to make way for conventional rubber plantations. The engineers and the Fraunhofer researchers are investigating the use of dandelions, from which latex – a liquid form of natural rubber – is extracted.

The preferred Russian dandelion can be grown even on poor soils and therefore will not complete with other agricultural crops. Another advantage is that the conventional rubber trees cannot be harvested for the first seven years, whereas dandelions keep on growing year by year. However, there is not yet enough of the wild variety available for production on an industrial scale. But at least now dandelions have been sufficiently optimized through breeding and selection to return stable yields. With reliable long-term experimental results, Continental is planning to use the new raw material in series production within ten years. In a different project, Fraunhofer scientists have developed their first tire prototypes with surfaces made of synthetic rubber. In tests they demonstrate better rolling resistance than natural rubber and 30 to 50 percent less abrasion.

Dandelion instead of natural rubber - Foto: Saad Chaudhry on Unsplash

The preferred Russian dandelion can be grown even on poor soils and therefore will not complete with other agricultural crops. Another advantage is that the conventional rubber trees cannot be harvested for the first seven years, whereas dandelions keep on growing year by year. However, there is not yet enough of the wild variety available for production on an industrial scale. But at least now dandelions have been sufficiently optimized through breeding and selection to return stable yields. With reliable long-term experimental results, Continental is planning to use the new raw material in series production within ten years. In a different project, Fraunhofer scientists have developed their first tire prototypes with surfaces made of synthetic rubber. In tests they demonstrate better rolling resistance than natural rubber and 30 to 50 percent less abrasion.

Tires for autonomous driving and clean air

Everyone is talking about autonomous driving. But what implications does it have for the tires? The next generation of passenger cars and trucks will have to satisfy different demands than those of today. For this purpose, Goodyear has developed its spherical “Eagle 360 Urban” tire. It enables autonomous vehicles to weave through the traffic in all directions – forwards, sideways, and even diagonally. This is to be made possible by a magnetic levitation system that does away with mechanical connections to the vehicle. The tread is created from elastic polymers using 3D-printing, and imitates the bionic structures of human skin. A foam-like material under the skin enables the tire to adapt flexibly to the road surface and the weather conditions. Sensor networks are present to ensure that the vehicle’s speed is automatically adjusted when the road surface is wet or slippery. At the same time, data are also exchanged with other vehicles and the traffic infrastructure.

 
Goodyear's tire concept "Oxygene"

Using artificial intelligence, the tire can continually optimize its behavior. Sensor systems can localize damage and adjust the tread accordingly. Materials will then flow toward the affected part and re-close the damaged area. And even if the Eagle 360 Urban is meant to be more of a thought-provoking idea than a feasibility study, it underscores the importance of tires in the future. The "Oxygene" concept tire that was unveiled in 2018 actually has moss in its sidewall. With the tire’s open structure and specially designed tread, the moss is intended to absorb moisture from the road surface, which can then circulate. This allows photosynthesis to take place, which releases oxygen into the atmosphere. Goodyear’s "Aero" is designed for flying taxis. When the vehicle is about to take off, the wheels rotate through 90 degrees and begin to function as rotors. The spokes are shaped so that they act as rotor blades and generate lift. Those were the good old days, when tires were just round!

Concept tires give new impetus to the discussion of intelligent, safe and sustainable mobility. Well-known tire manufacturers will be on site at the IAA Exhibition displaying their futuristic models. Get your IAA ticket and experience the mobility of tomorrow.