Method for estimating the side slip angle ( β stim) of a four-wheeled vehicle, comprising: - detecting signals representing the vehicle longitudinal acceleration (Ax), lateral acceleration (Ay), vertical acceleration (Az), yaw rate ( ψ̇), roll rate ( θ̇), wheels speeds ( V FL, V FR, V RL, V RR); - pre-treating said signals in order to correct measurement errors and/or noises, so to obtain corrected measurements of at least the longitudinal acceleration (a x), the lateral acceleration (a y), the yaw rate ( ψ̇) and the wheels speeds ( v FL, v FR, v RL, v RR); - determining an estimated vehicle longitudinal speed V x stim on the basis of at least one of the corrected measurements of the wheel speeds ( v FL, v FR, v RL, v RR); - determining a yaw acceleration ( ψ̈) from the signal representing the yaw rate ( ψ̇); - solving a time-depending parametrical non-linear filter, such as a Kalman filter or a Luenberger filter, describing the vehicle longitudinal and lateral speeds V x ^, V y ^ and longitudinal and lateral accelerations V x ^., V y ^. as a function of the corrected measurements of the longitudinal acceleration (a x), of the lateral acceleration (a y), of the yaw rate ( ψ̇) and the estimated vehicle longitudinal speed V x stim and of a filter parameter depending from at least one of the vehicle yaw acceleration ( ψ̈), yaw rate ( ψ̇) and lateral acceleration (ay) which adds a negative component to the lateral acceleration V y ^. determined by the filter itself, said filter parameter being selected such that said negative component reaches a maximum value when it is determined that the vehicle is moving straight on the basis of said at least one of the vehicle yaw acceleration ( ψ̈), yaw rate ( ψ̇) and lateral acceleration (ay); - determining the vehicle estimated side slip angle ( β stim) from said longitudinal and lateral vehicle speeds V x ^, V y ^ determined by solving the non-linear filter. - detecting signals representing the vehicle longitudinal acceleration (Ax), lateral acceleration (Ay), vertical acceleration (Az), yaw rate ( ψ̇), roll rate ( θ̇), wheels speeds ( V FL, V FR, V RL, V RR); - pre-treating said signals in order to correct measurement errors and/or noises, so to obtain corrected measurements of at least the longitudinal acceleration (a x), the lateral acceleration (a y), the yaw rate ( ψ̇) and the wheels speeds ( v FL, v FR, v RL, v RR); - determining an estimated vehicle longitudinal speed V x stim on the basis of at least one of the corrected measurements of the wheel speeds ( v FL, v FR, v RL, v RR); - determining a yaw acceleration ( ψ̈) from the signal representing the yaw rate ( ψ̇); - solving a time-depending parametrical non-linear filter, such as a Kalman filter or a Luenberger filter, describing the vehicle longitudinal and lateral speeds V x ^, V y ^ and longitudinal and lateral accelerations V x ^., V y ^. as a function of the corrected measurements of the longitudinal acceleration (a x), of the lateral acceleration (a y), of the yaw rate ( ψ̇) and the estimated vehicle longitudinal speed V x stim and of a filter parameter depending from at least one of the vehicle yaw acceleration ( ψ̈), yaw rate ( ψ̇) and lateral acceleration (ay) which adds a negative component to the lateral acceleration V y ^. determined by the filter itself, said filter parameter being selected such that said negative component reaches a maximum value when it is determined that the vehicle is moving straight on the basis of said at least one of the vehicle yaw acceleration ( ψ̈), yaw rate ( ψ̇) and lateral acceleration (ay); - determining the vehicle estimated side slip angle ( β stim) from said longitudinal and lateral vehicle speeds V x ^, V y ^ determined by solving the non-linear filter.