wheel bearing pre load
Bearing adjustment is part science and part art. It is based on a sense of feel from trial and error. It should feel smooth when spun, with the least amount of play. If it feels rough it is too tight or dirty. I had the most difficulty with tightening the jam nut after I made the adjustment. It seemed that the cone always got too tight while I was locking everything in place. You may find it easier to have a helper hold a wrench on one side while you hold the other cone and tighten the jam nut.