Reinforcement of Radial Tire Casing With Nylon 66

Abstract

The radial tire, now widely accepted by the American motor ing public, differs markedly from bias and bias belted tires in the demands placed on the casing reinforcement. The requirement for fatigue resistance is less and there is much less tendency toward "flatspotting," for example. This significantly broadens opportunities for cord selection and allows the full range of properties and economics offered by the various cord candi dates to be taken into account. A case in point is use of nylon 66 cord as a radial carcass reinforcement. While polyester, and to a much lesser extent, rayon cords are used in the U.S. as casing reinforcements for passenger radials, nylon appears to offer significant advantages in added durability and reduced manufacturing cost without sacrifice of performance or aesthetics. Nylon 66 is, in fact, used as the casing reinforcement of some passenger and light truck radials produced in Europe and Japan. This paper summarizes results from exploratory studies to define ways and the extent to which nylon 66 can be used effectively for radial casings. Standard polyester and nylon yarns were evaluated both as cords with conventional and reduced twist and as twisted yarns in 2-ply radial tires representative of passenger tires now on the market. Satisfactory performance was obtained from both types of reinforcement in many cases, but nylon emerged as the reinforcement offering the greatest potential for attaining maximum per formance at minimum cost.