Independent axial preloading of compressor and turbine disks in a gas turbine engine rotor is achieved by a dual tie shaft arrangement wherein a forward tie shaft engages forward and aft portions of a compressor hub within which the compressor disks are disposed to axially and compressively preload the compressor disks between the forward and aft portions of the compressor hub. An independent tie shaft engages an aft portion of a turbine hub within which turbine disks are disposed and an aft portion of the compressor hub to axially and compressively preload the turbine disks between the turbine and compressor hubs.