To provide a tire or a tire rim assembly fitted with a transponder to transmit an answer signal to a question signal given externally using as the source power an electromotive force induced in a coil to induce the electromotive force with an alternate magnetic field given externally, in which the coil and the transponder are mounted integrally, capable of enhancing the energy transducing efficiency when the transponder receives energy from the outside, and constructing small a separately provided alternate magnetic field generating device, or locating the alternate magnetic field generating device apart from the tire.

The tire or the tire rim assembly fitted with the transponder is structured so that soft magnetic rubber or a soft magnetic substance to gather the magnetic flux of the alternate magnetic field is provided in the region inside the coil in its radial direction.