Airless tyres - coming to a printshop near you
If airless tyres have anything to do with it, in future fleet drivers may have to visit a print shop not a workshop to get new ones.
Michelin forecasts that airless tyres could replace pneumatic ones on passenger cars by 2024 and its current prototype, the Uptis (Unique Puncture-Proof Tire System), is partially created using a 3D printer.
The Uptis promises to eliminate flat tyres, punctures and wear from over or under tyre inflation. It is currently being refined in partnership with General Motors who are trialling them on a Bolt AV in the USA.
Michelin has been developing airless tyres since 2005 but early models left a lot to be desired in terms of performance at speed. This is the first time a prototype has been fitted and tested on a road car.
Airless tyres aren’t replaced but reprinted
In constructing Uptis, Michelin has taken an aluminium wheel assembly and wrapped it in composite rubber with high-strength, resin-embedded fibreglass. A rubber tread bed covers the part of the tyre that touches the road and this can be replaced at any point through 3D re-printing. The tyres is environmentally-friendly as there’s less rubber required to make the tread bed than with a conventional all-round tyre. Thanks to new material and structural improvements, the Uptis can bear a car’s weight and perform well at speed.
3-D printing technologies can provide tread designs adapted to the users’ needs. When these change, due to seasons or usage, the treads can be modified for different uses.
Tweaking the airless tyre design
Bridgestone revealed its second-generation of air-free tyres in 2013 but it was a long way off commercial application. Alongside improving weight distribution, the unique spoke design left the sides uncovered (typical of airless tyres from all manufacturers) and had to be tweaked to stop debris getting in-between the spokes.
Where airless tyres score highly is that they are considered safer as they don’t blow out, which negates the need to change a flat tyre at the side of a busy road or dangerous motorway. They also remove the need for a spare, which frees up boot space in the car and lessens the overall weight of it, which equates to better fuel economy overall.
Airless and Autonomous
Airless tyres are especially suited for autonomous vehicles that demand near-zero maintenance to maximise their operating capabilities. To that end, Goodyear has developed a non-pneumatic (airless) tyre – NPT – and wheel assembly to support autonomous vehicle transportation that is being trialled in Jacksonville, USA. Part of the Ultimate Urban Circulator (U2C) programme, operated by the transportation authority, the tyres have been fitted on an Olli eight-person autonomous shuttle bus.
Precursors to the airless tyre include the “run-flat tyre” (also developed by Michelin), which has been fitted as standard on several luxury car brands such as BMW in recent years. These tyres are self-sealing in the event of a puncture and make it safe to drive for 50 miles to find a repair shop. However, the tyre is pricy and compromises ride comfort due to an inflexible tyre wall.
Michelin’s Tweel tyre, which it devised in 2005, has an outer edge of strong rubber (polyurethane) stretched around an inner supporting set of polyurethane spokes. The alloy wheel is then fitted centrally within this ring, providing a highly supportive wheel. Whilst removing many of the associated problems of a conventional or run-flat tyre, the Tweel has been described as noisy and suffering from excessive vibration, especially at high speed.
The future of airless tyres
Tires of tomorrow, including airless, will also communicate with the vehicle and driver/fleet managers by providing information on the usage history of the tire, as well as road conditions. Tire manufacturers are introducing tires equipped with RFID, or radio frequency identification tags.
Although not currently commercially available, it’s a high probability that airless tyres will catch on due to their high environmental credentials. As most tyre manufacturers are aiming for 90% recyclability in the coming years, every bit of an airless tyre is recyclable and many components are made from recycled materials.
Images: main image of Michelin's Uptis airless tyre on a Bolt AV. Inline image of Goodyear's NTP on an Olli AV shuttle bus