An inverted tooth chain drive system includes a sprocket supported for rotation about an axis of rotation and including a plurality of teeth defined relative to respective tooth centers. The tooth centers are spaced evenly in a circumferential arrangement about the axis of rotation, and each of the plurality of teeth includes an engaging flank. An inverted tooth chain is engaged with the sprocket and includes a plurality of rows of links each structured for inside flank engagement with the sprocket, with leading inside flanks of each row of links projecting outwardly relative to the trailing outside flanks of a preceding row of links. The leading inside flanks of each row are positioned to make initial meshing contact with the engaging flank of one of the sprocket teeth. At least some of the teeth are standard teeth and other ones of the teeth are flank-relieved teeth. The engaging flanks of the flank-relieved teeth are negatively offset relative to their respective tooth centers as compared to said engaging flanks of said standard teeth relative to their respective tooth centers. The root surfaces leading the flank-relieved teeth are raised relative to the root surfaces leading the standard teeth and are also inclined.