Unless the bearing shows unacceptable indications or the vehicle has ultrahigh miles, I would simply clean, regrease, and install bearing with new seals.

Unacceptable indications would include:

1. Presence of spalls on bearing working surfaces
2. Cracks in any of the bearing components
3. Particle denting of the raceway
4. Frosty (or matte) appearance on raceway
5. Discoloration from overheating
6. Corrosion of the bearing
7. Highly polished bearing surface (mirror-finish)
8. Darkening or fluting of the bearing surface
9. ANY evidence of loss of metal on the bearing surfaces

Stay away from that mechanic recommending to tighten the bearings.

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95 E320 Cabriolet, 159K