A belt pulley (1) for a belt drive and a plastic injection moulding method for producing the belt pulley are proposed. Said belt pulley (1) comprises an anti-friction bearing (2) and a running ring (3) which encloses the bearing outer ring (7), wherein an end side of the running ring has a multiplicity of moulding points (13) which run on the sector radii (R) of circular sectors which have a common centre point on the rotational axis (15) of the belt pulley and at least two centre point angles (alpha) of different size. Part of the circular sectors are to have sector radii, on which the moulding points have cross sections of different size. Here, the centre point angle of the adjacent circular sector on the side of the larger moulding cross section is larger than the centre point angle of the adjacent circular sector on the side of the smaller moulding cross section.