Fitting of bearings - Press fit
To press fit a bearing onto a shaft, the shaft has to be bigger than the hole in the bearing. The interference between the shaft and the bearing is prescribed by the manufacturer of the bearing. it has to be inside a specific tolerance otherwise the bearing will be to loose on the shaft and will not rotate with the shaft.  If the shaft is to big, it will interfere with the clearances between the races and the rolling element that will result in premature bearing failure.

The same will be when a bearing has to fit into a housing. The housing has to be smaller than the outside diameter of the bearing.

Video
Press fit bearing onto a shaft and into a housing