In most of the industrial applications, such as vehicular traction, when a Permanent Magnet Synchronous Motor (PMSM) can be used, a low cogging torque is required. The air gap variation, the magnet shapes and stator slots forms are the origins of cogging torque. In this work which aims at reducing cogging torque, we focus on the rotor magnet shapes optimizations. From intensive Finite Elements (FE) simulations of a Surface-mounted Permanent Magnet Synchronous Motor (SPMSM), 3-phases, 2-pairs of pole and 36 stator slots (3-circuits by pole and phase), a cogging torque reduction can be reached. The effect of different magnet shapes on cogging torque is studied in order to identify the optimal design for each one.