The article is aimed to construct the plots of speed range change, at which the necessary and sufficient condition of wheel rolling onto the rail head is satisfied, on the basis of generally accepted methodologies of the wheelset off-loading calculation. First of all, for the specific example, it is necessary to define the value of the train motion speed, at which it takes place the largest wheel off-loading on the curved section of the track with the existing oblique, to determine the minimal height of the oblique, at which the change of the train speed will not lead to the satisfaction of the necessary condition of wheel rolling onto the rail head. One should also construct a generalized scheme of checking the conditions of the rolling stock derailment if there is a railway track oblique of the certain value. In order to determine the influence of the train motion speed on the satisfaction of conditions of the car wheel rolling onto the rail head, it is necessary to solve the system of differential equations that describes the motion of the over-spring part of the rolling stock on the oblique track section under the influence of the forces applied to it. As a result of research carried out, there was obtained the value of train motion speed, at which the largest off-loading of the car wheel on the curved track section with oblique takes place. There was defined the minimal oblique value, at which the change of the train motion speed will not lead to the satisfaction of the necessary condition of the wheel rolling onto the rail head. There were constructed the plots of changing the speed range, at which the necessary and sufficient condition of car wheel rolling onto the rail head is satisfied. In the article, there was constructed the generalized scheme of checking the conditions of the rolling stock derailment if there is a railway track oblique. There were determined the speed ranges, at which the rolling stock derailment may occur if there is a railway track oblique of the certain value. There was defined the value of the train motion speed, at which the largest off-loading of the car wheel on the track curved section with the skew takes place. The obtained dependencies may be used for defining the safe range of the train motion speeds on the track sections with oblique of the certain value. They may be also used while carrying out the forensic railway-transport examinations.