Abstract: A method of testing wear of tires is presented. It comprises applying a single layer of reflective paint to a tread surface by spraying, and then measuring the intensity of light reflected from a matrix of blocks on the unworn tire. The tire is then run for a short distance and the wear on the tire is assessed by measuring the intensity of light at each block compared to the intensity before the test run. The wear rate is clearly indicated by the changing levels of intensity of reflected light. Multiple colors or layers of paint are unnecessary. Tread wear can be measured with greater accuracy than achieved by other paint tests. The test run can be considerably shorter than test runs utilizing other methods.

Abstract: Reversion resistance of a sulfur cured aircraft carcass rubber compound is greatly improved by incorporating, as anti-reversion agents, 1.5-6 phr of a mixture of zinc salts of one or more C.sub.8 -C.sub.10 aliphatic carboxylic acids and one or more monocyclic aromatic acids, and 0.8-2 phr of a bis-citraconimido compound. Much greater reversion resistance is obtained with a combination of the two anti-reversion agents than with either anti-reversion agent alone.