The Tweel offers a number of benefits beyond being impervious to nails in the road. The tread will last two to three times as long as current radial tires, Michelin says, and when it does wear thin, it can be retreaded. The tire maker has high expectations for the Tweel. The concept of a single-piece tire and wheel assembly is one that the company expects to spread to passenger cars and construction equipment and aircraft. The Tweel is in its infancy – “version 1.0” Thompson said, and only one set of car Tweels exists. A test drive in a Tweel-equipped Audi A4 sedan on roads around Michelin’s research center proved to be far less exotic than the construction method or appearance would suggest. The prototype Tweels are noisy, as Thompson warned they would be, because the spokes vibrate.The all new airless tire from Michelin recently came out into the publics eye early 2005. Although it appears to be a pretty good idea and concept, they probably will not be available to the general public soon. I have looked at the idea and think it is cool, although I don’t know what to think of the center rim selection that you haven’t got a choice with. I’m sure that the police will probably not like the idea because the spike strips will definitely be ineffective with a set of these on your ride. The ride and handling seem to be very effective.

The first automobile to use air-filled tires was a race car built by André and Edouard Michelin in the early 1890’s. More than a century later, the French company founded by the Michelin brothers is so identified with pneumatic tires that its mascot, Bibendum, is a man made of little else.

Now, after decades spent persuading the world to ride on air, the company has begun work on an innovation that could render the pneumatic tire obsolete. Engineers at Michelin’s American technology center are working on what they call Tweel, a combined tire and wheel that would not go flat because it contains no air.

The tire maker has high expectations for the Tweel. The concept of a single-piece tire and wheel assembly is one that the company expects to spread to passenger cars and construction equipment and aircraft.

The Tweel does have several flaws (aside from the name). The worst is vibration. Above 50 mph, the Tweel vibrates considerably. That in itself might not be a problem, but it causes two other things: noise and heat. A fast moving Tweel is unpleasantly loud. Long-distance driving at high speeds generates more heat than Michelin engineers would like.

Another problem involves the tire industry. Making Tweels is quite a different process than making a pneumatic tire. The sheer scale of the changes that would need to be made to numerous factories, not to mention tire balancing and mounting equipment in thousands of auto repair shops, presents a significant (though not insurmountable) obstacle to the broad adoption of airless tires.

Because of these flaws, Michelin is not planning to roll out the Tweel to consumers any time soon. “Radial tire technology will continue as the standard for a long time to come,” said Michelin’s press release touting Tweel development. They are initially working on Tweel use in low-speed applications, such as on construction vehicles. The Tweel is perfect for such use because the high-speed vibration problems won’t come into play, and the ruggedness of the airless design will be a major advantage on a construction site. Michelin is also exploring military use of the Tweel.

Michelin isn’t the only company working on an airless tire design. Resilient Technologies is developing their own airless tire, known as the NPT (non-pneumatic tire). That company is using a more aggressive development and marketing strategy aimed at military use. The NPT is based on a different configuration of spokes, but the general idea is the same as the Tweel.

For manufacturers, the Tweel offers an opportunity to reduce the number of parts, eliminating most of the 23 components of a typical new tire as well as the costly air-pressure monitors that will soon be required on new vehicles in the United States.

Manufacturers have devoted an increasing amount of attention to tires that allow motorists to continue driving, at a reduced speed, for at least 100 miles, or 160 kilometers after a puncture. Several such designs are available, providing peace of mind for travelers and cutting the need for spare tires. Michelin sells them under the Pax name.

The Tweel, mounted on a car, is a single unit, though it actually begins as an assembly of four pieces bonded together: the hub, a polyurethane spoke section, a “shear band” surrounding the spokes and the tread band – the rubber layer that wraps around the circumference and touches the pavement.

While the Tweel’s hub functions as it would in a normal wheel – a rigid piece that attaches to the axle – the polyurethane spokes are flexible, to help absorb road impacts. The shear band surrounding the spokes effectively takes the place of the air pressure, distributing the load. The tread is similar in appearance to a conventional tire.

One shortcoming of a tire filled with air is that the pressure is distributed equally around the tire, both up and down as well as side to side. That property keeps the tire round, but it also means that raising the pressure to improve cornering – increasing lateral stiffness – also adds up-down stiffness, making the ride harsher.

With the Tweel’s injection-molded spokes, those characteristics are no longer linked, holding the potential to improve handling response. The spokes can be engineered to give the Tweel five times as much lateral stiffness as pneumatic tires without losing ride comfort.

Almost everything else about the Tweel is undetermined at this early stage of development, from serious matters like cost to more frivolous questions like the possibilities of chrome-plating.

.. via fastcoolcars ..


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