A run-flat support ring, which is a component mounted upon a rim inside a tire to extend the distance the tire may travel at reduced or zero inflation pressure, is provided having an integrated shelf design that enhances the handling characteristics of the support ring under run-flat conditions and may also lower the overall mass of the support ring in certain applications. In addition, the support ring has one or more features that improve the process of mounting the support ring onto a rim and better tolerate variations, within manufacturing tolerances, in the respective diameters of the rim and the support ring.