The strength of passenger seats and seat mounts are usually evaluated on the basis of personal vehicle tests. In particular, the backrest, its mounting, and the seat mounting are subjected to horizontal forces and evaluated. None of these tests, however, accounts directly for forces exerted by unbelted passengers thrown from behind into the rear of the backrests. The purpose of the paper was to investigate the validity of the testing procedure for commercial vehicles. Result were based on deceleration and rebound tests with dummies.The tests showed that none of the passenger seats or their mountings was damaged by the deceleration of its own mass. However, all test seats were deformed by dummies striking them from behind under simulated collision conditions. Seat mountings remained undamage, though. It was concluded that the personal vehicle tests should not be directly applied to commercial vehicles because the forces applied on the backrests are not directly comparable in the two cases.