Tweel
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The Tweel (a portmanteau of tire and wheel) is a prototype tire designed by Michelin. The tire uses no air and therefore cannot burst or become flat. Instead, flexible polyurethane spokes are used to support an outer rim. Handling gains have been cited as a reason to adopt this type of motor vehicle tire. If problems with the prototypes (such as excess vibration and noise at higher speed) are resolved, the first applications for the tire may be in the military where a flat-proof tire would be advantageous to maneuvering vehicles in difficult or dangerous areas.
Currently, the Tweel is being used for low-speed, low-weight applications, such as wheelchairs and construction equipment (for example, a skid loader). Tests on production cars have shown it is within 5% of a conventional tire and wheel's rolling resistance. If Michelin's prototypes go as planned, models for cars may appear around 2016.
The Tweel has been presented in a variety of applications. Eventually it may be able to outperform conventional tires since it can be designed to have high lateral strength (for better handling) without a loss in comfort.
[edit] Design
The Tweel consists of a cable-reinforced band of conventional "tire" rubber with molded tread, a shear band just below the tread that creates a compliant contact patch, and a series of energy-absorbing polyurethane spokes. The rectangular spokes can be designed to have a range of stiffnesses, so engineers can control how the Tweel handles loads. The inner hub contains a matrix of deformable plastic structures that flex under load and return to their original shape.
