Experimental observations of the cyclic deformation and temperature rise in Mallory tubes during testing are described. The analyses of the data explain the temperature rise in terms of heat generated by the cord and rubber during the cyclic deformation. Using the measured temperature rise and the heat generative characteristics of cord and rubber, the effective strain amplitude of the cyclic deformation is calculated. This effective strain amplitude is compared and found to be consistent with the strain amplitude measured from photographs of the tube contour during testing. The study also reviews some of the factors affecting the results of the test and proposes an explanation for the differences in durability between tubes reinforced with nylon 6 and nylon 66..