Abstract: A bearing unit for a wheel hub assembly for motor vehicles, the bearing unit having an axis of rotation (X) and having two radially outer raceways, two radially inner raceways, two rows of rolling bodies, the bearing unit having tribological parameters whose values affect the magnitude of the frictional forces between the respective raceways and rolling bodies of the rows of rolling bodies, wherein at least one value of a tribological parameter is minimized or maximized to reduce the magnitude of the frictional forces as a function of the relative position along the axis (X) of a line of action (W) of loads acting on the bearing unit and of the plane of axial symmetry (Z).