January 7, 2005
Michelin invents combined wheel and tire without air pressure
Vancouver, British Columbia – Michelin has released details of its new Tweel, a combined tire and wheel. Developed in the U.S. at the company’s technology centre in Greenville, the non-pneumatic Tweel has the potential to transform the automotive, military, construction and personal mobility industries in the years ahead, said the president of Michelin research.
“Major revolutions in mobility may come along only once in a hundred years,” said Terry Gettys, president of Michelin Americas Research and Development Centre. “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.”
The heart of the Tweel innovation is its 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.
The Tweel still delivers pneumatic-like performance in weight-carrying capacity, ride comfort, and the ability to “envelope” road hazards, said the company.
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 standard production application. Additionally, Michelin has increased the lateral stiffness by a factor of five, making the prototype unusually responsive in its handling.