Used to pack the hub bearings in an old jeep cj I had. I remember the manual saying to tighten the nut until the bearings had just a bit of drag noticeable when you spin the wheel, then back off until the wheel spins free. Is always how I did it, and I only had the wheels fall off once or twice. (Kidding)

 

I like to run just a bit of pre-load on the bearings, to avoid sloppy steering. Tighten the nut by hand, while turning the rotor, until the bearings seat, then maybe a quarter turn more.