Michelin Lets Air Out of Future Tire Innovation

French tire maker Michelin has revealed a peek at what might be the next generation of wheel and tire technology. Michelins’ integrated tire and wheel combination is missing one ingredient that is vital for traditional tire performance … air. The company unveiled the first real-world fitments for its revolutionary “Tweel” — which operates entirely without air.

“Major revolutions in mobility may come along only once in a hundred years,” said Terry Gettys, president of Michelin Americas Research and Development Center in Greenville, S.C. “But a new century has dawned and Tweel has proven its potential to transform mobility. Tweel enables us to reach levels of performance that quite simply aren’t possible with today’s conventional pneumatic technology.”Michelin’s Tweel is in production and available as an enhancement for future iBOT mobility systems. Invented by Dean Kamen, the iBOT mobility device has the ability to climb stairs and navigate uneven terrain, offering mobility freedom impossible with traditional wheelchairs. Additionally, Segway LLC’s Concept Centaur, a prototype that applies self-balancing technology to a four-wheel device, has also been equipped with Tweel to increase its performance potential. Beyond these first real-world applications, Michelin 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. At the recent North American International Auto Show, Michelin released video of promising Tweel performance on an Audi A4.

The heart of Tweel innovation is its deceptively simple looking hub and spoke design that replaces the need for air pressure while delivering performance previously only available from pneumatic tires. The flexible spokes are fused with a flexible wheel that deforms to absorb shock and rebound. Without the air needed by conventional tires, Tweel still delivers pneumatic-like performance in weight-carrying capacity, ride comfort, and the ability to “envelope” road hazards. Michelin has also found that it can tune Tweel performances independently of each other, which is a significant change from conventional tires. This means that vertical stiffness (which primarily affects ride comfort) and lateral stiffness (which affects handling and cornering) can both be optimized, pushing the performance envelope in these applications and enabling new performances not possible for current inflated tires. The Tweel prototype, demonstrated on the Audi A4, is within five percent of the rolling resistance and mass levels of current pneumatic tires. That translates to within one percent of the fuel economy of the OE fitment. Additionally, Michelin has increased the lateral stiffness by a factor of five, making the prototype unusually responsive in its handling. Checking tire pressure, fixing flats, highway blow-outs and balancing between traction and comfort could all fade into memory.