Abstract: A central hub which may contain a bearing or a bushing has a central radial web with reinforcing spokes on each side of the web. The web terminates in an outer rim. An inner rim slightly spaced from the outer rim extends from each side of the web and defines annular cavities on each side of the web. At arcuately spaced intervals in the web between the rims are small perforations. A tire is molded about the outer rim and extends into the annular cavities between the outer and inner rim and through the perforations to form a mechanically integral structure with the web and rims. Additionally thread guard discs or covers may shroud the space between the hub where it protrudes axially beyond the web and the inner face of the inner rim. The covers may be supported either by the bearings in the central bearing apertures of the hub or from the outer faces of the hub itself.