USA: Michelin Tweel combines wheel and tyre in one
Michelin has released new details of its Tweel technology, the fusion of the tyre and the wheel.
Developed in the US at the company's technology centre in Greenville, the non-pneumatic Tweel is said to have the potential to transform the automotive, military, construction and personal mobility industries.
The heart of the Tweel is its simple looking hub and spoke design that replaces the need for air pressure while delivering performance previously only available from pneumatic tyres. The flexible spokes are fused with a flexible wheel that deforms to absorb shock and rebound with ease. Without the air needed by conventional tyres, Tweel is claimed to deliver 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 tyres. This means that vertical stiffness (which primarily affects ride comfort) and lateral stiffness (which affects handling and cornering) can both be optimised, enabling new performances not possible for current inflated tyres.
The Tweel prototype, demonstrated on the Audi A4, is within 5% of the rolling resistance and mass levels of current pneumatic tyres. That translates to within 1% 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.