A piston assembly includes an annular body defining a groove, with a ring disposed within the groove. The piston assembly includes a centering device disposed within the groove between an inner face of the ring and a root of the groove. The centering device centers the ring concentrically within the groove when the ring is in an uncompressed condition, prior to installation into a bore of an engine block, to prevent the inner face of the ring from moving radially outward beyond an outer edge of the groove when the ring is in the uncompressed condition.