if two way communication is desired between spare wheel 12 and vehicle 16 controller 28 can be a programmed microcontroller or an application specific integrated circuit asic and can be integrated with memory 26 one or more of the other components of system 10 spare wheel 12 is also equipped with a pressure sensor 32 operatively coupled to the interior of tire 20 and a transponder activation coil 34 controller 28 receives input from motion sensor 22 and pressure sensor 32 and formats this input for wireless transmission by transmitter 24 to vehicle 16 as a signal in accordance with a predetermined communications protocol communication by controller 28 can be at predetermined intervals or can be initiated in response to stimulation of transponder activation coil 34 by a signal emanating from vehicle 16 as explained below controller 28 also formats a protocol compatible marker signal for transmission by transmitter 24 referring to fig1 vehicle 16 includes receivers 36 a 36 d mounted thereon receivers 36 a 36 d are adapted to receive signals transmitted by transmitter 24 receivers 36 a 36 d can be transceivers if two way communication is desired between spare wheel 12 and vehicle 16 alternatively a single receiver such as receiver 36 a.