The dynamic behavior of commercial vehicles has been studied over the last 25 years, mainly in Europe and America. Earlier tests took place as far back as the thirties with the handicap, that tire properties were vastly unknown at that point in time.Today adequate computer systems have yielded the capability for studies of complex vehicle systems.Although being by no means complete, the knowledge of dynamic behavior of automobiles is considered state of the art, while that for commercial vehicles is still largely empirical.Some of the unique problems of commercial vehicles are: huge payloads and a wide range of variable masses which create high side to side and or fore aft load transfers, due to a high center of gravity, mutual influence of the various units of a truck combination by means of couplings, e.g. different accelerations or decelerations of tractor and trailer. While vehicle dynamics basically consist of lateral, longitudinal and vertical motions with the corresponding forces, moments and accelerations, this paper focuses on lateral dynamics solely, i.e. handling, rearward amplification, frequency response and rollover.This study was undertaken as part of the program for the development of the Freightliner Advanced Concept Truck (FACT).