Electronics device for a tire having an extensible antenna and a tire having such a device

An electronic communication device for a tire includes a radio device and an antenna intended to be attached to or embedded in a tire, the antenna being spirally or helically shaped to absorb tensile and bending stress applied by the tire. The antenna body may be a wire formed of spring steel, brass or zinc coated spring steel, or spring brass. A coating of insulating material coats the radio device and antenna for mounting on or in, and operation in, a tire structure.