An annular apparatus is embedded in a substantially nonconductive elastomeric material (22) located within the toroidal region of a pneumatic tire (10). The apparatus is coaxially positioned with respect to the tire or wheel and preferably is embedded in the tire at its equatorial plane (EP), and includes a radio-frequency transponder system (30), including an integrated circuit chip (28), and optional sensors in the chip or associated with the chip. The integrated circuit chip (28) of the transponder system (30) has at least the capacity to transmit data relating to tire or wheel identification. The antenna (26) comprises a springy steel wire or filament. Electrical leads (32) of the chips (28) are electrically associated with each end of the antenna (26).