This is not quite right for tanks such as PzIII & IV and Panther yes Schurzen did help protect this sides from Anti-tank rifles and latter shaped charges but on Tiger I and more so Tiger II this is not the case the lower sides were 80mm thick this is thicker than the front plate of a Sherman plus this area is between the sponson and top of the tracks so is only a small area, the side skirts on Tiger II are designed primarily as mudguards the shape also hinders soldiers climbing on the tank from the sides as the mud guards protrude over the tracks.