The increasing requirement for vehicle safety enforces us to do further investigation research for the stability control system of commercial heavy duty vehicles. About 50% of the these accidents are caused by vehicle spin-out and rollover. Hence, advanced stability control for heavy duty vehicle needs to be implemented. In this paper, the vehicle gravity position is estimated in using Auto-Regressive (AR) method since the commercial vehicle dynamic characteristics is changeable due to its unspecified load. And the rollover behavior is predicted by both the gravity position and the rolling condition such as rolling behavior. Thus rollover preventing system is proposed.