Semi-trailer tank vehicle with lowered center of gravity

The tank has, at its front part (1), tapered sections (2, 3) in which the front section (2) is less widened than the section (3) that leads into a tubular part (4) forming the main part of the tank body. The section (2) has, at its lower part, a cradle (5) with connecting units to be connected to a towing vehicle. The radius of curvature of the lower part of the sections is smaller than that of the upper part.