Puncture-proof bike tire runs without air

A number of designs for airless tires for cars have been put forward over the years, but one U.S. company says its new version is intended for bicycles. Colorado-based Britek Tire and Rubber has been working on an airless tire it calls the Energy Return Wheel, where a rubber tread and sidewall is stretched over an internal scaffolding of rods and cushions that allows the tire to give in the same way a pneumatic tire does. Mounted on carbon fiber rims, rubber is stretched tight around the outside and can be adjusted to let the tires run harder or softer, NBC News reported. A series of elastic cushions occupy the space that would ordinarily be filled with air. The tires take their name because the stretching of the internal rubber layer allows elastic potential energy to be stored within the wheel, Britek founder Brian Russel said, then the stored energy is returned and converted into forward momentum.