The present document describes a ladder rack system for displacing a ladder between a loading/unloading position on one of a side, a front and a rear of a vehicle and a stored position on a roof top of a vehicle, the ladder having a first ladder end and a second ladder end, the ladder rack system comprising: a first assembly to be mounted on a first end of the roof top for receiving the first ladder end; and a second assembly to be mounted on a second end of the roof top at a distance from the first end for receiving the second ladder end, the second assembly comprising: a pivoting rail to be pivoted between the loading/unloading position in which the pivoting rail extends substantially vertically or at an angle on the one of a side, a front and a rear of the vehicle and the stored position in which the pivoting rail extends longitudinally along the roof top; and a carriage slidably mounted on the pivoting rail for receiving the second ladder end and for sliding along the pivoting rail when the pivoting rail is in the loading/unloading position; wherein when the carriage is slid on the roof of the vehicle, the pivoting rail can be pivoted in the stored position longitudinally along the roof top.