A rack assembly for an automatic dishwasher having opposing side portions, at least two axles extending outwardly from each of the opposing side portions, and a roller wheel mounted to each axle. Each roller wheel roller wheel has a hub adapted to be fixedly attached to the axle, and a wheel rotatably mounted to the hub. A plurality of separators that define pockets is integrally molded with one of the hub or the wheel. Each pocket is adapted to contain one ball bearing such that no two adjacent ball bearings make contact.