Abstract: To enhance active vehicle safety and unified chassis control, we present a cascade method that evaluates each of the tire longitudinal forces. This new approach is inspired by the disturbance input observer theory based on a simplified wheel dynamics model. Our cascade method estimates the lateral tire forces by approximatingthe longitudinal tire forces based on a planar bicycle model. The vehicle onboard sensors record engine torque and rotational speed, wheel cylinder pressure, wheel angular speed, steering wheel angle, lateral acceleration and yaw rate measurements. Our method for tire forces is evaluated using simulation experiments in a high-fidelity vehicle dynamics software application, veDYNA. A comparison analysis is done via the extended Kalman filter method. Experimental results reveal the excellent performance of the new cascade method for tire forces estimation.