The profile has a peripheral groove (1) formed on peripheral portions (11, 12) with maximum groove depth. A rib flank (5) is formed in a radially inner extension area (8) in one of the portions with a slope or a curvature that is different from a slope or a curvature of the other portion. The rib flank in the former portion exhibits a larger inclination angle and/or a larger curvature radius than in the latter portion and another rib flank in the former portion exhibits a smaller inclination angle and/or a smaller curvature radius than in the latter portion.
