The concept of an airless tyre isn’t entirely new – Michelin debuted the spoked Tweel way back in 2005 – but the French manufacturer has now revamped the concept via the Uptis (Unique Puncture-proof Tyre System) revealed last week at the Movin’ On mobility summit in Montreal, and the company claims the new tech will be production-ready by 2024.
Michelin says the revolutionary Uptis tyre will initially be offered in rim sizes ranging from 15 to 18 inches for mainstream vehicles, and its introduction could go some way towards eliminating the 200 million tyres prematurely scrapped each year due to puncture or irregular wear due to under-/over-inflation. Measured by weight, this would save the equivalent of 200 Eiffel Towers of waste material.
Although the Tweel is already used on golf karts, lawnmowers, construction equipment and so forth, its construction makes it unsuited to passenger-vehicle applications.
Speaking to Wheels, Michelin CEO Florent Menegaux explains: “The Tweel was made of polyurethane, so the spokes were fabricated from a sort of plastic. With the Uptis, the spokes are made of a rubber-based compound, like in a tyre, and therefore you get very different properties.
“So, it’s the same concept, but with very different physical characteristics. It’s easier to produce, is less expensive and enables you to drive faster. It also consumes less energy than the Tweel and offers better dynamic capabilities overall,” he says.
“The rim itself is made of aluminium, while fibreglass, steel and aramid synthetic fibres are used to reinforce the outer perimeter. The spokes are made of reinforced rubber, as in a normal tyre. The shape of the spokes is very different to the Tweel. They flex like a tyre, so while it looks similar, it’s a very different object to the Tweel.”
Michelin has entered into an agreement with General Motors to trial the tyre on a fleet of Chevrolet Bolt EVs to gain some real-world data on wear rates and other parameters for the Uptis as Menegaux says it’s very difficult to simulate “all the aggression a tyre will experience during its life”.
He adds: “We have had a long-standing partnership with General Motors and they are sufficiently interested to share with us the financial risk in developing the tyre. That said, they will not gain exclusivity to the tyre when it eventually becomes production ready.”
Menegaux says he’s driven an Uptis-equipped vehicle, and he claims it feels for all intents and purposes like a conventional tyre: “You can feel there’s a slight difference, but it’s very subtle, even at reasonably high speeds and with aggressive steering inputs. With the Tweel, its plastic spokes meant it couldn’t offer the shear and flex you need to deliver acceptable ride quality and cornering capability.”
“In fact, with the Tweel we even had to redesign the suspension of the car it was fitted to as it was relaying all the impact from the road to the chassis. The design and material composition of the Uptis has eliminated that, so from that perspective it’s no different to a regular tyre.”
Menegaux says the focus with Uptis for now is to develop it solely for bread-and-butter passenger vehicles. Specialised applications will come later, if at all. “At this stage, commercial vehicles such as trucks are not in the frame for Uptis as there are constraints due to weight,” he says. “For now, we are just making sure that it works for passenger vehicles.”
High-performance and off-road applications and off-road applications are also off the table, says Menegaux. “A partially deflated pneumatic tyre floats on sand, but obviously that wouldn’t be the case with the Uptis…. this is made more for urban mobility. Similarly, the Uptis can’t withstand the extreme high-speed cornering that, for example, a Michelin Pilot Sport Cup tyre can, so it won’t be a substitute for that either. In the future maybe, but I’m not sure we’ll go in that direction.”
The price of the Uptis vis-à-vis a conventional tyre will be largely dependent on the quantities produced, as the cost will obviously decrease once production is scaled up. “We live in an industry where scale matters in terms of cost, but one thing I can say is that the Uptis is a lot less expensive to produce than the Tweel because the spokes are made of materials that we already use for our existing tyres,” Menegaux says.
“As for replacement, we are currently evaluating whether we retread, so instead of replacing the centre and the spokes, you simply replace the tread. There’s also the possibility of replacing a spoke if one of these is damaged. We also know how to separate the rim from the spokes, so there isn’t the need to replace both components simultaneously.”
But is Michelin potentially curtailing its own sales volume by introducing a tyre that, by definition, will need to be replaced less often? Menegaux’s answer to that: “We are never afraid of innovating and I’m not worried about what we could lose in terms of overall sales volume.”