Abstract: An annular hollow tire with an inner surface having a generally positive radius of curvature and at least one circumferentially extending rib portion on the inner surface with a negative radius of curvature located at an area of the tire subject to high stresses to mitigate the stress concentrations in that area of the tire. The method of making the tire includes the steps of providing a tire mold with a core having a selected circumferentially extending portion on the outer surface with a negative radius of curvature for forming the rib portion, filling the space between the core and mold surface with an elastomeric precursor, heating to set the precursor and form the tire and removing the tire from the mold and the core from the tire.