A method of manufacturing a rust-proof, leak-proof and air-impervious welded tire rim by providing a pair of rim bodies each of which includes a peripheral bead and at least one of which includes a valve seat defined by an opening and with the rim bodies being welded to each other along an exterior circumferential weld; liquid-cleaning the welded rim; and applying to the entirety of all exposed surfaces of the rim an air-impervious coating of resilient copolymeric material whereby any porosity of the circumferential weld is sealed against air migration and the rim beads and valve seat are all totally coated with a resilient air-impervious coating for effectively sealing against air migration in association with a tire bead and an air valve body, respectively.