An apparatus determines a condition and relative location of an inner tire and an outer tire of a tire pair. Each tire has an associated tire-based sensor assembly that senses a tire condition, senses acceleration, and transmits, in response to its associated acceleration signal, having a unique tire identification and associated sensed tire condition. A tire rotation sensor senses rotation of the tire pair during vehicle movement and provides a tire rotation signal indicative thereof. A vehicle-based controller associates each of the unique identification signals with one of the inner tire location and the outer tire location responsive to a phase relationship between the received transmitted signals from the tire-based sensor assemblies and the tire rotation signal.