Abstract: A method and for mounting a flat printing plate on a cantilevered plate cylinder of a printing press, particularly in a lithographic web-fed rotary printing press. The printing plate is bent into an essentially cylindrical shape and inserted into a hollow tube. The tube and plate are slid from the side over a mandrel mounted on the plate cylinder. The mandrel expands the printing plate to a condition where the mandrel has an outer diameter which is smaller than the inner diameter of the tube and which is larger than the outer diameter of the plate cylinder. The tube and printing plate are slid down the length of the plate cylinder, and the ends of the plate are then locked using a lock-up device. The tube is then removed from the plate cylinder. Air bearings may be used on the mandrel or the plate cylinder, and the mandrel may be expandable.