A vehicular rear slider window assembly includes a fixed window panel, a movable window panel, a frame portion fixed relative to the fixed window panel, and an opening through the fixed window panel. The movable window panel is movable along upper and lower rails of the frame portion between closed and opened positions. A slider bearing system includes a guide element disposed at least partially along the lower rail and a carriage disposed at a lower perimeter region of the movable window panel. The guide element includes a bearing element that is slidably and non-rotatably received at a bearing receiving portion of the carriage. The carriage moves in a direction parallel to a longitudinal axis of the bearing element when the movable window panel moves between the closed position and the opened position.