Abstract: This paper proposes nonlinear observers(virtual sensors) of vehicle states(vehicle sideslip angle and velocity of the center of gravity(v_g)) and tire-road forces.The observers strictly use low cost sensors potentially used or actually mounted in recent vehicles(longitudinal/lateral accelerations,yaw rate,steering angle and angular wheel velocities).The estimation process is based on two blocks in series.The first block estimates tire-road forces based on a sliding-mode observer(SMO),while the second one calculates sideslip angle and velocity of the center of gravity using the single-track model.In SMO,a hyperbolic tangent switching function is used to overcome the chattering problem.Validations with the simulator ve-DYNA and the HILS(hardware in the loop simulation platform) indicate the accuracy and the robustness of the proposed observers.