Modern wheel bearing hub assemblies are manufactured to high precision, and close tolerance. Final machining of the close fit parts takes place when the unit is put into service (installed on vehicle). Final machining creates excess heat that if not managed properly will not only damage the sealed non replaceable grease, also the surface finish and hardness of the metals will be damaged reducing the life span of the part.
After installation of wheel bearing hub assembly, drive short a distance (under 2 miles) and slow speed (under 50mph). This will allow the close fit parts to "wear" together a.k.a. final machining. Repeat this procedure several times increasing the distance, but keep the speed slow, this helps prevent too much heat being generated and ruining the permanent grease.
Most of all, do not just pick up vehicle from shop with new hub/hubs, and then hop on the interstate and go 70mph for 4 hours.
This procedure is known as "breaking in", and can be met with much skepticism. My experience has been, that the more tenderly I have treated any new high precision machined parts into service, the longer they have lasted.
