Purpose. An integral and essential feature of the modern wagon fleet is its large scale. For the entire fleet of rolling stock, even the smallest structural changes take on enormous proportions. The aim of the work is a theoretical study of the influence of the inertial characteristics of bodies of various types of freight rolling stock, taking into account the loading mode and the movement speed, on their main dynamic and interaction indicators with the track structure. Methodology. Theoretical studies were carried out by the method of mathematical and computer modeling of the dynamic load during the movement of some types of freight cars: gondola cars model 12-532, hopper cars for transporting coal model 12-4034 and flat wagons model 13-401 on standard bogies 18-100 at speeds in the range from 50 to 90 km/h on curves of small and medium radii. Findings. The analysis of theoretical studies of the dynamic qualities and interaction indicators of freight rolling stock and the railway track is presented. In the course of theoretical studies and after modeling taking into account the oscillation processes of freight cars at different loading modes the dependences of the main dynamic indicators on the movement speed were obtained. Originality. The influence of inertial characteristics of bodies of various types of freight rolling stock and loading modes on the dynamic load of a car was first explored in order to solve the problem of predicting the rolling stock dynamics and indicators of its interaction with the track. The results of theoretical studies taking into account the movement speed along curved track sections of small and medium radius were obtained. Practical value. The presented calculation results make it possible to determine the optimal values of such parameters as dead weight, height of the mass center and car base length when solving the problems of modernizing the operated car fleet and determining the reserves for increasing their carrying capacity. They make it possible to solve the problems of finding the optimal directions for modernizing the rail vehicle; contribute to the creation of technical conditions for the manufacture of new and modernization of the operated freight cars and are aimed at increasing the level of reliability and safety of the transportation process in modern conditions on the railway transport.