Michelin rolls out airless tyre

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Michelin wheeled out its airless tyre at the North American Motor Show yesterday, describing it this time as "the first real-world fitment" (see link below for earlier story). And it might coming to a car near you soon.

Michelin's Tweel is in production and available as an enhancement for future iBOT mobility systems for the disabled. Invented by Dean Kamen, the iBOT mobility device can climb stairs and navigate uneven terrain, offering mobility freedom impossible with traditional wheelchairs.

Beyond these first real-world applications, Michelin said it has additional projects for Tweel on construction skidsteers and a variety of military vehicles.

The most intriguing application may be Michelin's early prototype Tweel fitment for passenger cars. The mobility company released a video of Tweel running under an Audi A4.

"The Tweel automotive application, as demonstrated on the Audi, is definitely a concept, a stretch application with strong future potential," said Michelin's research boss Terry Gettys. "Our concentration is to enter the market with lower-speed, lower-weight Tweel applications. What we learn from our early successes will be applied to Tweel fitments for passenger cars and beyond."

What is a Tweel?

The heart of Tweel innovation is its simple-looking hub and spoke design that replaces the need for air pressure while delivering performance that Michelin claimed is akin to that of pneumatic tyres. The flexible spokes are fused with a flexible wheel that deforms to absorb shock and rebound easily. Without the air needed by conventional tyres, Tweel still delivers pneumatic-like performance in weight-carrying capacity, ride comfort, and the ability to envelop road hazards, reckoned the company.

Michelin said it had found that it can tune Tweel performances independently of each other, which is a significant change from conventional tyres. This means that vertical stiffness (which primarily affects ride comfort) and lateral stiffness (which affects handling and cornering) can both be optimised, improving performance and enabling new performances not possible for current inflated tires.

The Tweel prototype, demonstrated on the Audi A4, is within five per cent of the rolling resistance and mass levels of standard tyres so fuel economy should be almost unaffected, said Michelin. Michelin said it had increased the lateral stiffness by a factor of five, making the prototype unusually responsive in its handling.

Future of Tweel technology

For Michelin, Tweel is a long-term vision that represents the next step in a long path of industry-changing innovations. The lessons learned from Tweel research are being applied to improve conventional tyre performances, according to Michelin. In the future, Tweel may reinvent the way that vehicles move. Tyre maintenance and balancing between traction and comfort could all fade into memory, said the company.

Comments (30) Join the discussion on the forum

  • annodomini2 10 Feb 2006

    Would be interesting to see average lap times between the A4 on Tweel and on conventional tyres (manufacturers standard fit), assuming you could get an equal comparison.

    And vertical g difference (i.e. hitting bumps) between the 2.

  • dinkel 10 Feb 2006

    Optically that looks pretty stupid . . . and what if something gets stuck in the tire: slingshot or messed up arch, or worse.

    Smart idea though. An intergrated wheel-rim combi would be nice. I can see the benifits for trucks and other pro-used vehicles.

  • scared but happy 10 Feb 2006

    I presume the final model will have filled in sides as I suspect the demonstation models have open sides to show the workings. I also expect that to create a one hell of spray when going through puddles.

    Great idea though. I just wonder if you can retro fit the tyres onto standard rims? Also as the 'pressure' remains the same hot/cold that means tyre wear should be reduced.

    But thinking about it for a minute if the tyre maintains itself would they be doing themselfs out of a few sales?

  • ubergreg 10 Feb 2006

    To gain mainstream market acceptance (at least initially) I'm sure it wouldn't be much of a stretch for the manufacturer to 'clothe' the tweel spokes to look like a conventional tyre. It's probably also possible for them to introduce a low-profile size - though I wonder how far the ride would deteriorate.

    At this point, I'm wondering how the costs would compare to an conventional radial or run-flat tyre... sounds like good technology to me.

  • Code Monkey 10 Feb 2006

    Concept cars will be coming soon though with the side walls removed, to allow them a total rubber band look, imagine the side deformable section of the wheel in the same colour as the wheel would make a micra look like it was fully pimped running on dubs, i think thats the correct phrase

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