A turbine rotor for a gas turbine engine includes a disk rotationally disposed about a central axis. The disk includes a bore, a rim and a web disposed radially between the bore and the rim. The bore includes a fore surface including a fore web transition portion, a fore ramp portion radially inward of the fore web transition portion and having a substantially linear portion and a fore base transition portion radially inward of the fore ramp portion. The bore also includes an aft surface including an aft web transition portion, an aft ramp portion radially inward of the aft web transition portion and having a substantially linear portion and an aft base transition portion radially inward of the aft ramp portion. A base portion of the bore includes a spool engagement surface, a first arm extending in an aft direction and a second arm extending in a fore direction and a radially extending first transition portion connecting an aft end of the spool engagement surface to a radially inward portion of the first arm and a radially extending second transition portion connecting a fore end of the spool engagement surface to a radially inward portion of the second arm.