Abstract
In this paper the analytical expressions are derived for the critical speeds for the sidewise skiddinng conditions of the truck-trailer axles. Also, the minimum value of the adhesion coefficient is determined for the ensuring of the cornering with a given turning radius.We consider both the uniform uphill motion(driving operation mode) and the uniform down-hill motion. In the case of the vehicle braking it is supposed that the braking force is applied on the rear axle of the truck-tractor only by the engine and possible by the retarder.