Abstract: An inflatable bag (17) for use in exhaust powered tippers is constructed from blanks of flexible air tight material using a side wall template (10) and end wall templates (11, 12). The blanks are made so that the finished bag when fully inflated assumes an oblique cone-like shape (17) with rounded ends (19, 20). The side wall material is preferably a fabric having waft and weft fibres of uniform tensile strength so that the tension in the side wall is in the longitudinal direction as the bag inflates in order to reduce the tendency of the bag to rotate on its couplings. The invention can be provided in kit form where the bag is coupled for limited movement to load transmitting end plate (21, 22) for retro fitting the bag to a vehicle.