Abstract: The system for guided steering of a set of rear wheels of a semi-trailer comprises a pulling vehicle and a semi-trailer having rear wheels which are turnable with respect to a chassis of the trailer to turn from a neutral position to one or the other side of the semi-trailer for generating steering of the vehicle in one direction with respect to a neutral position. The system further comprises power generating apparatus to act on the rear wheels to generate turnings of the rear wheels, activating apparatus mounted in the driver's cabin of the vehicle for operation by the driver of the vehicle for generating a steering of the rear wheels independently of the steering of the vehicle as well as locking structure operated from the driver's cabin, in a first position for generating locking of the rear wheels in the neutral position, and switchable from the first position to a second position, where the rear wheels are released and brought to turn by activation of the activating apparatus.