UHF passive RFID tags embedded in tires have a deep impact on tire life cycle management and tire monitoring. In this paper, the authors present the power transmission of UHF passive embedded RFID in tires. In UHF passive embedded RFID systems in tires, the bidirectional radio link between reader and tags goes through air and tires. The total path loss contains reflection loss at tire-air boundaries and attenuation loss in the tires. The power transmission is based on the permittivity of tires and tire-air boundary conditions.