The clearance tolerances for bearings do overlap to some degree, hence it is possible that the clearance in a C3 could be the same as a C4. In reality though you will find that a particular factory will tend to statistically be at the upper or lower end of an allowed tolerance band. Whilst another factory will statistically be in a different area of the tolerance band. You could take the chance, but we would advise you not to, and that your application details be looked at carefully. A quick assesment of the various application factors balanced against the tolerance range of the bearing clearance will determine if there is any danger in the bearing radially preloading itself.