Radical airless tyre has half the rolling resistance and is cheaper to make
April 30, 2005 Michelin’s radical new Tweel announced in January this year looks set to be the next big thing in tyre technology but recent news from Amerityre on a very similar technology suggests there will be strong competition in the airless tyre market, as more than one manufacturer is close to market. Amerityre has successfully completed high-speed testing of its experimental non-pneumatic or “zero-pressure” polyurethane tyre in testing for FMVSS 129 compliance, the safety standard governing the testing of non-pneumatic car tyres. The advantages of the polyurethane tyre are many according to Amerityre including much cooler running temperatures (less wear), much lower rolling resistance (amounting to a reported 10% decrease in fuel consumption) and the ability to produce a complete tyre inside a few minutes significantly simplifying and reducing the cost of the manufacturing process.
The zero pressure spare tyre is under development by Amerityre in response to a growing concern among consumers and government agencies such as The National Highway Traffic Safety Administration (NHTSA) for post-crash fires caused by fuel leakage in high-impact rear collisions. A high-pressure pneumatic spare tyre’s close proximity, in most cases, to the fuel tank can be an explosion hazard for vehicles involved in high-impact rear collisions. A zeropressure spare tyre reduces the risk of causing an explosion.
In addition to collision safety, Amerityre’s objective is to offer equal or better performance to that of comparable rubber high-pressure spare tyres. Although the tyre is being developed for “temporary” use, Amerityre believes that a zero-pressure spare tyre can be safely operated at 50 mph for over 2,000 miles. Consumers won’t need to worry about air pressure in polyurethane elastomer spare tyres, unlike traditional high-pressure spare tyres, which lose pressure through permeation over time. Loss in air pressure greatly affects the performance of a high-pressure spare tyre. The zero pressure spare tyre, on the other hand, will give drivers an always ready solution in the event of a failed pneumatic tyre.
During testing the polyurethane elastomer compound tyre showed great results. The test tyre ran at 50 miles per hour with increasing loads for beyond the required 34 hours.
Comparison testing with a traditional run-flat radial has also shown the Amerityre prototype to have nearly half the rolling resistance, which Amerityre claims translates to more than a 10% increase in fuel economy for a car equipped with these tyres.
Amerityre uses a proprietary injection molding system to produce its passenger tyres which can produce a finished tyre including bead and belts in a few minutes.
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That\'s a big contributor to why they are noisy. If you look at the tread on most tires you\'ll see the blocks are different sizes. The reason is to prevent harmonic vibrations from causing noises at various speeds.
The goal is to have the tread designed to not have a harmonic vibration at any speed.
Having the airless tire structure all evenly spaced is ensuring they\'ll be noisy and vibrating, especially at higher speeds.