We’re going through an electric vehicle transition, but pneumatic tires feel constant. Invented in 1888 by Dunlop, but patented in the automotive industry from 1891 onwards by Michelin, the pneumatic tire has improved significantly since then. But the basic concept of tires has persisted for more than a century. Now, according to Michelin, it may be time for a new type of tire that has been discussed for more than a decade – not including inflation.
The addition of air to automobile tires was probably essential to the widespread adoption of mechanized transportation. Suspension and dampers can only go so far in providing the ride quality and handling we demand in a modern vehicle. The air in the tires has provided an extra cushion to soften the experience for the car’s occupants and maintain the vehicle’s stability. The side effect is also that less road noise is transferred to the car.
Michelin is exploring the future of tires with its UPTIS airless concept.
However, while there have been some incremental improvements over the years, the pneumatic radial tire that Michelin invented as early as 1940, going on sale in 1972, remains the leading technology. Seeing that this was an area that could use an update, Michelin unveiled the UPTIS (Unique Anti-Puncture Tire System) at the Movin’On Summit 2019. But the idea goes further than that. Over ten years ago Polaris produced an ATV that came equipped with airless tires because they were much more resilient to off-road damage.
Michelin airless tires in space?
Ten years later, Michelin is convinced that airless tires will be essential to mobility and improving environmental impact, although there is still no timeline for when. At the Le Mans 24 Hours race in June, the company showed off an airless design it had created to meet NASA’s brief for the Artemis program’s lunar rover. It is clear why airless tires may be preferred when driving on the airless surface of the moon. But they also have many benefits for less extraterrestrial applications, on a surface with a breathing atmosphere.
Michelin has suggested airless tires for the Artemis lunar rover.
One problem with pneumatic tires is punctures – a particular problem with the UK’s horribly potholed roads. In fact, 20% of tires worldwide end up being scrapped before their typical lifespan is reached. This is not just from the wells, but can be caused by irregular wear due to pumping them to the wrong pressure. This results in the replacement of 1 – 1.6 billion tires per year – a phenomenal issue for the environment, which has been further emphasized by the transition to EVs.
This is one area where switching to airless tires can help. They cannot be set to the wrong pressure because they have no air in them. This prevents that form of damage and they are more resilient to other types of damage as well. Pneumatic tires can be damaged in a way that does not cause deflation, but does risk it, meaning they will need to be replaced for safety reasons. For example, sidewall damage may not immediately puncture the tire, but compromises structural integrity. In the UK this is usually an MOT failure requiring replacement. However, current airless models don’t even have sidewalls. Damage to the spring fins is still possible, but Michelin argues that this is unlikely to happen and will not lead to catastrophic failure like a pneumatic tire blowout.
Future models of airless tires may not be like the wheels we’ve known before.
The life of an airless tire can be further extended through retreading. This is something that has been practiced for over a century. It is common practice for large commercial vehicles such as trucks and buses, but not for cars, due to the size and complexity of the tires. Car tires are expected to provide high performance, such as coping with road speeds of more than 100 mph. There is also a consumer perception that this would not be safe, nor would the shorter life of the rest of the tire make this type of repair economical. However, it is estimated that airless tires can last up to three times longer than pneumatic tires, potentially lasting between 50,000 and 100,000 miles, depending on driving conditions and maintenance. This can make them more economical to retread than pneumatic car tires. A good quality all-season car tire lasts between three and five years or 20,000 to 60,000 miles – but as already mentioned, it may end up being replaced long before that due to damage.
Is the future of Michelin tires airless?
Airless tires require further material innovation compared to pneumatic ones. The outer shell will be made of rubber similar to traditional wheels, but the complex internal structure that replaces the pressurized air is generally manufactured from glass fiber reinforced polyurethane. The rim will remain aluminum, steel or an alloy, but may be a more integral part of the wheel, so the airless tire cannot be removed. Weight resistance is unlikely to be adjustable, the way we inflate tires more when carrying a heavy load. The airless tire will need to be calibrated against the maximum weight the car is rated to carry.
In addition to the lunar vehicle prototype unveiled at Le Mans, Michelin has road-tested its UPTIS airless tires with La Poste in France and with DHM in Singapore. Tesla is also reported to be in talks with Michelin to use the company’s airless tires on its cars. However, Michelin admits that there are still no standards for airless tires in the same way that pneumatic tires are evaluated. Alongside Michelin’s UPTIS, Bridgestone has an airless concept and Hankook has iFlex. Goodyear has ventured even further into science fiction with its spherical Eagle 360 Urban concept for autonomous cars. But in general, most tire manufacturers are not prioritizing airless yet. However, there are clear benefits to airless tires, so they may soon be another step towards making transportation more environmentally friendly.