plot diagram of a force elongation behavior of cords 18 19 and 20 according to this invention each consisting of two superposed flat wires of a rectangular cross section and of equal thickness the cords differ one from the other by a number of twists per unit length the results are tabulated in the following table i fig4 shows a similar force elongation diagram of a prior art reinforcing cord 21 23 each consisting of two steel wires of circular cross section and each having a different number of twists per meter the results are also tabulated in the following table i the effective cross section area of cords 18 19 and 20 according to this invention corresponds to that of prior art cords 21 22 and 23 table i______________________________________cord wire twists per elongation k sub maxnr cross section meter at k sub max ______________________________________18 b h 2 0 2 4 10019 b h 2 70 3 6 9720 b h 2 100 4 4 9621 circular 0 2 0 10022 circular 70 2 5 9723 circular 100 2 7 96______________________________________ it is apparent from the plot diagrams of fig3 and 4 that the elongation of the reinforcing cords according to this invention in response to the applied force can be substantially increased in comparison to prior art cords assembled of round wires whereby the maximum permissible tensile load in both types of cords is comparable and slightly decreases with increasing widths in this example two prior art commerically available reinforcing cords are compared with a reinforcing cord according to this invention in the following table ii cords 24 and 25 correspond to prior art cords a and b in.