Abstract: The invention relates to a pneumatic spring (2) essentially comprising two terminal elements (4, 6), a pressure-tight roll bellows which is arranged therebetween and made of a flexible elastomeric electroconductive material (14), a strengthening carrier (16) formed by two cord-fibre plies (16a, 16b) which are made of threads (18), crossed at an angle (?) and vulcanised inside said bellows. In order to determine the height (h) of the spring, in a preferred embodiment, said two cord-carcass plies (16a, 16b) are provided with a certain number of highly conductive threads (18a) which are arranged at the beginning and the end of each ply in a parallel direction to each other, thereby forming two conductive strips (24a, 24b). Said conductive strips (24a, 24b) are disposed oppositely to each other and electrically connected at the end of the roll bellows (8) in such a way that a conductive loop (24) is formed and each strip is used as a branch for an alternating current measuring bridge (28).