A track assembly is to be mounted on a drive axle of a vehicle. The track assembly has a frame, at least one leading idler wheel mounted to the front of the frame for rotation about a transverse leading idler wheel axis, at least one trailing idler wheel mounted to the rear of the frame for rotation about a traverse trailing idler wheel axis parallel to the leading idler wheel axis, and a single drive wheel assembly. The drive wheel assembly includes a sub-frame removably securable to the frame in any one of a plurality of longitudinal securement positions on the frame, and a drive wheel rotationally mounted on the sub-frame for rotation about a drive wheel axis. The drive wheel is operatively connectable to the drive axle of the vehicle. A pair of track assemblies is also described. A vehicle having the pair of track assemblies is also described.