In a rotor assembly for an exhaust gas turbocharger including a turbine wheel and a compressor wheel mounted on a common shaft for joint rotation wherein the turbine wheel consist of a metal aluminide or of a high-temperature resistant titanium alloy, the turbine wheel and the compressor wheel are disposed on the shaft in spaced relationship by way of a bearing sleeve via which the turbien wheel and the compressor wheel are axially firmly engaged by axial clamping structures associated with the common shaft.