Originally Posted by Greg in France

Modern wheel bearings are enclosed factory-sealed units, both inner and outer in a housing, all greasing and tolerances etc etc factory set and the housing sealed round them. there are no clearance/adjustment issues as they are just slapped on the stub (if, that is, the entire unit, stub hub and all does not come as a single unit) and the nut done up to 90 ft llbs and that is that. Unless the vehicle gets racing-type cornering and braking loads they will last for ever.
With our earlier technology, unchanged in design since pre-WWII, failures - rare as they are - come about from bad adjustment, water and grit ingress caused by the bad adjustment etc etc.
On the Jaguar rear suspension rear hubs, however, which nobody ever touches, or ever greases, where the bearing clearances are factory-set even if built up at the factory from individual components, and which it is impossible to do anything to without major effort, the bearings DO last for ever!