A pneumatic tire and wheel rim assembly is disclosed in which the rim bead seats are defined by grooves having radially directed side portions which retain the associated tire bead against movement in an axial direction and each rim bead seat includes means in engagement with the tire bead to restrict rotation of the tire bead relative to the bead seat. Preferably said means comprises a plurality of projections formed integrally with part or all of the grooves which engage the associated tire bead to restrict rotation. Each projection may comprise a circumferentially extending rib or a tooth.