I pre-load wheel bearings by feel, rather than a specific torque spec.

After greasing the bearings, snug the nut. After spinning the rotor a couple times, the bearings usually loosen up a little. Snug the nut again and install the keeper and cotter pin.

The bearings should not spin freely when installed. In other words, you should be able to feel a LITTLE resistance when you turn the rotor.