The header (6) comprises a front and rear wheel assembly (11,12), each assembly comprising an axle (13) and two wheels (14a,14b). Each wheel assembly is coupled to the main body of the header (6) by an actuating system (15) comprising an actuator mechanism (40,41) for actuating a swivel movement of the axle (13) and the wheels (14a,14b), to bring the wheel assembly to or from a road transport position. The front and rear wheel assemblies are equipped with tie rod arrangements for steering the header (6) when it is transported on the road. The wheels of the wheel assemblies (11,12) are operated as caster wheels. The tie rod arrangement of the front wheel assembly (11) is coupled to a pivotable base (60) connected to or connectable to a drawbar (55). The wheel assemblies comprise respective actuators (66,68) which are synchronized so as to synchronize the position of the front and rear wheels.
