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Rolling resistance measurements were made on a sample of twenty-four retreaded and four new truck tires spanning a variety of constructions, tread patterns and tread depths. Examination of the results showed some relationship between three construction features and the resulting rolling resistance values. These are (a) Radial or bias carcass construction, (b) Tread pattern, and (c) Tread depth. The latter two characteristics can over-ride radial or bias construction effects. The effect of tread compound could not be analyzed in this limited test program. Good quality retreaded truck tires can exhibit comparable rolling resistance with new truck tires.

A method has been developed for calculating the internal temperature distribution in an aircraft tire while free rolling under load. The method uses an approximate stress analysis of each point in the tire as it rolls through the contact patch, and from this stress change the mechanical work done on each volume element may be obtained and converted into a heat release rate through a knowledge of material characteristics. The tire cross-section is then considered as a body with internal heat generation, and the diffusion equation is solved numerically with appropriate boundary conditions at the wheel and runway surface. Comparisons with buried thermocouples in actual aircraft tires shows good agreement.

Strain gage instrumented transducers were used to measure the cord loads at a number of locations in several different automotive tires loaded against both flat and cylindrical road wheel surfaces. The two basic types of cord load fluctuation encountered in all automobile tires have been identified from these measurements, and the most severe location for cord load fluctuations has been closely bracketed. By these measurements, it has been possible to show that for each tire definite relations exist between the cord loads induced while running on a cylindrical drum and while running on a flat surface. The maximum cord load fluctuations in a tire are the same for the NBS roadwheel and flat surface when the tire is loaded against the roadwheel with a load of between 85 and 90% of that used on the flat surface.

In this paper, the effects of fluctuating torque on loosening of a tightly seated bolt are investigated. Tests over a wide range of bolt stresses and loosening torques are reported and equipment developed for determination of such effects is described. It is shown that a definite functional relationship exists between the stress on a typical bolt, the oscillatory loosening torque that is applied, and the number of cycles before the bolt becomes loose. The effects of these relationships follow a clearly defined law, although they are, of course, influenced by a number of additional variables.