A wheel hub unit having a rotatable hub provided with an axially outer flange and a bearing unit. The bearing unit providing a radially outer ring, a radially inner ring and a plurality of rolling bodies positioned respectively between the radially outer ring and the hub and between the radially outer ring and the radially inner ring. The radially inner ring has a finished axial length which ensures a predetermined value of an axial preload of the bearing unit and a finished axial length is defined by the following formula: X′=(X+ΔX)−ΔX1