This paper presents the design and simulation tests of a lane keeping assistance system for passenger vehicles based on a piecewise affine state feedback controller. The design of the proposed lane keeping system takes into account the entire domain of lateral tire forces through piecewise affine approximations of the tire forces nonlinear behavior. The computation of the control law is casted as Bilinear Matrix Inequalities optimization procedure which is solved using the V-K-method to find a piecewise quadratic Lyapunov function and the state feedback gain. Simulations show the improved performance of the controller on degraded road adhesion conditions.