Most tires go flat because something punctures right through the tread.
A new type of tire is supposed to seal itself. The tests included two brands of self-sealing tires, one made by Uniroyal and another from General . The inside of the tire is coated with a gooey gel-like material. If you puncture the tread, the gel is supposed to plug the hole. In an example, testers saw that the puncture was effectively sealed by the gel material.