An isolated center tread rim idler is disclosed. The isolated center tread rim idler includes an idler body, and a circular rim including a radially outer portion configured to engage track bushings of a track assembly. The circular rim also includes a radially inner portion of less width than the radially outer portion. The radially inner portion is configured to cooperate with an outer circumferential surface of the idler body. The circular rim includes a curved transition portion between the radially outer portion and the radially inner portion. A resilient ring engages the curved transition portion. A side plate is fastened to a side of the idler body, and the side plate includes a portion engaging the resilient ring.