Before I install new stainless steel spokes and chrome plated brass spoke nipples, I replace the front wheel bearings. The rear wheel does not have wheel bearings. Instead it is mounted directly to the rear drive. Since the rear wheel does not have an axle, there is no need for wheel bearings.
Here is a link to the documentation on how I do this work and a short YouTube video that summarizes the procedure.
VIDEO: 1983 BMW R80ST Replace Wheel Bearings & Set Pre-Load