Michelin Aims to Start Tyre Revolution
The answer is – when it is a Tweel. Michelin has been demonstrating the direction that it would like to take tyres by exhibiting one of its most recent developments at Detroit’s North American International Auto Show.
The Tweel is an airless tyre/wheel concept that consists of a band of tread attached to a set of flexible polyurethane spokes. According to Michelin executives, this design makes for a “virtually indestructible vehicle tyre” that can be tuned for handling. The same executives also concede that any practical applications could be as much as 15 years away.
The Detroit exhibition is not the first time that Michelin has presented the Tweel at an international exhibition. The company also showed its new design at the Paris Motor Show last autumn where it is said to have been the subject of a number of inquiries from car manufacturers. Speaking at the Detroit show, company representatives said they hoped its latest appearance would result in more manufacturers testing the prototype tyres.
As a tyre/wheel hybrid, any future, large-scale introduction would have major repercussions on the automotive industry. But before that happens it would have to be accepted by more manufacturers. Even so the people behind the polyurethane spokes are optimistic. “Major revolutions in mobility may come along only once in a hundred years,” said Terry Gettys, president of Michelin Americas Research and Development Center. “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 Tweel is based on what Michelin calls a “deceptively simple looking hub and spoke design” this replaces the need for air pressure while delivering performance. Also the fact that there is no air means the tyres cannot puncture in the conventional sense, bringing a whole new meaning to the word run-flat. The spokes are fused to a flexible wheel that deforms to absorb shock. Michelin says that even though there is no air in its product, it can still deliver “pneumatic-like performance” in weight-carrying capacity, ride comfort, and the ability to “envelope” road hazards.
Another significant development is that, according to Michelin, the performances of each Tweel can be independently tuned. This means that vertical stiffness (affecting ride comfort) and lateral stiffness (for handling and cornering) can both be optimised. Other technical improvements include weight and rolling resistance. According to the company, Tweels produce within five per cent of rolling resistance and mass levels of pneumatic tyres. This is said to translate to within one per cent of the fuel economy of the standard production application.