A work vehicle comprises a vehicle body, a work implement, a track frame, a sprocket, an idler, a plurality of small track rollers, and first and second large track rollers. The track frame comprises opposite first and second end sections, and opposite upper and lower sections. The sprocket and idler are rotatably mounted to the first and second end sections, respectively, to movably support an endless track. The small and large track rollers are rotatably mounted to the lower section between the sprocket and idler and are unmovable in vertical and horizontal directions of the track frame. The small track rollers are all disposed between the first and second large track rollers. Each small track roller defines a respective small track rolling surface having a respective first tread diameter and each large track roller defines a respective large track rolling surface having a respective second tread diameter greater than each respective first tread diameter.