The design of engine vehicles cannot be imagined without considering the mutual relations in the complex dynamic system Driver - Vehicle - Environment. Inconsistency between any of the connections in the mentioned system leads to disruption in the functioning of the system as a whole, which in some cases can lead to catastrophic consequences. The necessity of knowing the parameters of behavior on the road for traffic safety is especially emphasized. Therefore, in practice, it is researched in different conditions. It was considered expedient to establish the reliability of some tests used during the research of truck behavior on the road. A detailed analysis, based on the study of the interdependencies of the controlled (steering wheel angle and torque at the steering wheel) and partially controlled excitation (vehicle velocity) concluded that the overtaking test is the most acceptable for these researces