The declaration of conformity of the N and O Category vehicles used for hazardous goods transport under ADR Part 9 in accordance with ECE R 111 obtained from the manufacturer for the tanks / tankers with less than 4 bar test pressure is required according to the relevant legislation. For this purpose, ECE R 111 for the Rollover Stability of Tankers has been calculated; the adequacy of the tanker's balance in terms of technical requirements can be proved.