A wheel weight system is provided for attachment to the disc (11) of a tractor or other vehicle wheel (10). The system comprises an annular axially inner weight (12) for attachment to one side of the wheel disc via a first set of bolts (15) extending axial through the inner weight and the wheel disc. Also, the system comprises an axially outer weight (21) for the attachment to the axially inner weight by a second set of bolts (24) which extend through the axially outer weight into the axially inner weight. A set of removable centring members (23) are provided which cooperate with apertures (27, 28) in the axially inner and outer weights to centre the axially outer weight relative to the axially inner weight.