In this paper an active brake control to reduce the rollover risk of heavy vehicles is proposed. The brake system is activated when the vehicle comes close to rolling over. In order to enhance the performance of the active brake, the braking algorithm is extended with an estimation procedure of the side force coefficient in order to use it in control. The estimated value of the side force coefficient is applied as an additional scheduling variable in the linear parameter varying (LPV) based control design. The brake is activated at the appropriate time and reduces the rollover risk without delay when the changing of the side force coefficient is taken into consideration in the LPV model, thus the control guarantees the safe operation of the brake. The control design is based on the LPV model of yaw-roll dynamics of heavy vehicles. In the control design both the performance demands and the model uncertainties are taken into consideration