Tires in the Future

The pneumatic tire has served drivers and passengers well on road and off, but a new line of airless tires could change all that. One design -- the Tweel Airless Tire – was introduced by Michelin in 2005.

The name is a combination of the words tire and wheel because the Tweel doesn’t use a traditional wheel hub assembly. Mounted to the axle is a solid inner hub, which is surrounded by polyurethane spokes arrayed in a pattern of wedges. A shear band is stretched across the spokes, forming the outer edge of the tire (the part that comes in contact with the road). The tension of the shear band on the spokes and the strength of the spokes themselves replace the air pressure of a traditional tire. The tread is then attached to the shear band. The Tweel looks sort of like a very large, futuristic bicycle wheel.

Image © 2007 Michelin North America, Inc. Michelin Tweel ™ Airless Tire

When the Tweel is put to the road, the spokes absorb road impacts the same way air pressure does in pneumatic tires. The tread and shear bands deform temporarily as the spokes bend, then quickly spring back into shape.

Why the Tweel?
If you’ve ever taken a ride in an old-fashioned carriage with wooden wheels, you know what a difference a pneumatic tire makes. However, pneumatic tires do have drawbacks. The main problem, of course, is that a puncture of the tire results in total failure. Military planners are especially concerned with tires being blown out by gunfire or explosion shrapnel. Obviously, an airless tire can’t be disabled by a single puncture. So something like the Tweel would be useful in a military setting.

Unfortunately, the Tweel has several flaws of its own. 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. Long-distance driving at high speeds generates more heat than Michelin engineers would like, so Michelin is not planning to roll out the Tweel to consumers any time soon. For now, they’re 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.

Monowheel Vehicles So, you know wheels are an important part of a vehicle – whether it’s a bicycle, a car, a school bus or an 18-wheel truck. But what if the wheel were the vehicle? If you’ve seen a certain Capri Sun commercial, you have an idea of what we’re talking about. But it’s not something new – monowheel vehicles have been around since the late 1800s! Check out http://www.wheelsurf.nl/ and http://www.theriotwheel.com/ for two current-day monowheel concepts. Monowheel aficionado Kerry Mclean holds the world landspeed record for the fastest monowheel run.