PURPOSE: To improve longitudinal balance and turning performance by a construction wherein the captioned vehicle equipped with six wheels has front and rear wheels arranged in small diameter and center wheels in large diameter and further the lower end of center wheels made lower than that of front and rear wheels.

CONSTITUTION: A front wheel 3, a center wheel 4 and a rear wheel 5 are supported rotatably on a frame 1 in front loader. The front wheel 3 and the rear wheel 5 are small in diameter and the center wheel 4 is large in diameter. Further, a lower end position X of the center wheel 4 is taken somewhat lower than a straight line L connecting a lower end position Y1 of the front wheel 3 and a lower end position Y2 of the rear wheel 5. Where a bucket B is charged with soil and sand, a vehicle weight distribution gives front balance, the leading edge side of the vehicle comes down consequently around an axle 4a of the center wheel 4, and thus a load is supported chiefly by the four wheels. With high stability in a large tread, a turning performance like spin turn can be improved accordingly.