New Cord Increases Shock Resistance
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EIGHT plies of Tyrex, a new rayoncellulose cord specifically designed for car and truck tyres, are claimed by Courtaulds, Ltd., the manufacturers, to provide the strength of 12 standard plies. It is believed that nearly all new cars in the United States are now equipped with Tyrex-based tyres and that already 10 per cent. of current British production uses the same material.
A high-tenacity, continuous-filament yarn, Tyrex is manufactured by a modified Tenasco process. It has a breaking load rating of 35 lb., compared with the 23 lb. of the original Tenasco material introduced nearly 20 years ago. The reduc lion in plies for a given rating is reflected in reduced heat-build-up at high speed. Although initially more expensive than standard materials, the cost of Tyrex is offset by a saving in weight without any sacrifice in other desirable tyre properties.
Tests conducted by impartial research agencies in America indicate that Tyrexcorded covers showed a 20 per cent, advantage in tread wear over nylon-baied tyres, and as much as 30 per cent. in impact and shock tests. The new material remains stable at temperatures exceeding 250° C. (the melting point of nylon) and resists the reduced adhesion between cord and cover at elevated temperatures.