Nine tire cord materials were evaluated on the Firestone SCEF fatigue tester modified to permit flexing at a series of angles (52.5 to 0 deg) including those used in bias and radial bodies, and in a cross-ply construction to simulate the cord interaction in bias body and belt constructions. Angle studies showed that whereas certain high modulus materials, such as fiberglass and Fiber B, would not be expected to flex well in bias bodies, they might in radial bodies. High angle flexing showed rayon poorer for fatigue than nylon or polyester, but equal in cross-ply. Other findings were the generally higher fatigue resistance (1) of the first than of the second generation Fiber B, and (2) of the higher than of the lower twists in each material comparison made. Fatigue results of belt candidates (rayon, fiberglass, Fiber B, polyvinyl alcohol, and nylon 66 obround monofil) differed widely, although all have shown durability in passenger tire belts. The preferred test angle for belt correlation has not yet been established.