An apparatus determines a position of a tire on a vehicle including a tire-based sensing unit, each tire on the vehicle having an associated tire-based sensing unit. Each tire-based sensing unit includes a first sensor mounted for rotation with the tire and for generating a first sensor signal indicative of such rotation, a second sensor mounted for rotation with the tire and for generating a second sensor signal indicative of such rotation, and a transmitter for transmitting a signal indicative of a phase relationship between the first and second sensor signals. An axle position sensor is provided for determining each tire-based sensing unit position relative to a front and rear axle of the vehicle and provides an axle position signal for each tire-based sensing unit. A controller monitors the transmitted phase signals of each tire-based sensing unit and the determines axle position signals. The controller compares the tire-based sensing unit phase relationships for possible tire locations considering the determined axle positions of the tire-based sensing units, determines a confidence value by weighting the compared phase relationships, compares the phase difference of each tire-based sensing unit relative to the phase difference of other tire-based sensing units for each possible vehicle tire location, and associates each tire-based sensing unit with a vehicle location in response to the confidence values.