This paper considers the feasibility of equipping the main landing gears with electric motors for the aircraft traction during the taxi phase. Those electromechanical wheel actuators make possible a "Green Taxi" operation by considerably reducing the on-ground carbon emission. Moreover, this will enable important fuel saving for short distance flights with high frequency of landing and take-off. In this work, direct drive wheel actuator is considered for energy efficiency and mechanical reliability. Two possible locations of the actuator are examined and the weights of the corresponding electric machines are compared. The most weight efficient location is then selected. A high torque density permanent magnet machine is then designed to fit in this envelope and to satisfy peak torque, weight and flux weakening capability requirements. The design procedure as well as several technologies adopted to maximize the torque density are presented.