In recent years there has been much interest in problems involving the noise prediction and reduction inside and outside the vehicle. Tire/road exterior noise has been considered to be the major vehicle exterior noise source. However, this paper describes an investigation into the characteristics of the air pumping noise mechanism in terms of source locations and directionality. Some rubber tire/road air pumping noise measurements are presented, whereas some predicted results are computed based on the boundary element method (BEM) to display some parameters which are found to be difficult to be obtained experimentally. The influence of tire contact patch shape and the tread profile on air pumping of tread grooves are also investigated with the aid of simple profiles, one with lateral grooves, one with circumferential grooves and one with combined lateral and circumferential grooves in addition to the standard production profile with inclined grooves and the real profile with combined and complex tread pattern. The results indicate that air pumping noise mechanism has an effective contribution to the total tire/road exterior noise at driving speed below 50 km/h.