This work is about the steady state vibration of a rotor bearing system. The rolling bearings are modeled as two degrees of freedom elements where the kinematics of the rolling elements is considered, so are the internal clearance and the Hertz contact nonlinearity. The steady state solution of the system is achieved by the harmonic balance method, validated by a numerical integration using a three-point-centered finite difference scheme. The number of harmonics employed in the harmonic balance method is examined to find the satisfactory quantity of harmonics that can describe the system dynamics. The contact regimes in the rolling elements are also explored.