Abstract This paper presents the analysis of local stress increases at the contact zone between the inner and outer segments of telescopic booms of truck cranes. A portion with a relevant length was singled out of the outer segment and a mathematical model was created describing its stress–strain state as a function of geometrical parameters. The obtained results were verified by the finite element method as well as by experimental testing of the truck crane TD-6/8. Comparison of results revealed high compliance between the analytical model and the results obtained by the finite element method and experimental testing, which confirmed all the hypotheses. The presented methodology as well as the verified analytical expressions give guidelines for optimum design of box-like telescopic segments and other structures with local stress increase in contact zone.