To make effective use as a loading space or a working space by shortening a rear tread for the width of a cabin more than the one for ordinary use, and ensuring a vertical space to the outside of a rear tire behind the cabin.

In the case of a truck whose cabin 1 is wide, as a rear axle 3 mounted on a frame 2, a rear tread which is shorter than the one for ordinary use, namely, a rear axle used in the truck of standard cabin is used. By mounting the shorter rear axle 3, it is possible to ensure a vertical space to the outside of a rear tire 4 behind the cabin 1.