Abstract: A pair of specially configured tire mounting rims are adapted for attachment to the axle hub of an existing vehicle for converting from single to dual wheel mount configurations. The wheel mounts include one dish arrangement which incorporates a substantially flat radial web plate including appropriately spaced holes for attachment to axle bolt positions so that the rim channel generally overlies the axle terminating assembly. The other wheel mount has an interior web which extends in a convex or conical relation with matching bolt holes for placement over the axle bolts. The convex or conical web plate of the second wheel mount is arranged with sufficient extension so as to retain the tires on both mounts in separated relation while providing dual wheel support for the vehicle.