Satisfactory performance of steel ribbon belted radial tires of standard basic design is possible. The key to good fatigue life is that flexure is accommodated by shear of the rubber between the plies instead of by compression as in a twisted cord. Belt angle controls part of the fatigue mechanism but stress and lifetime are insensitive to its value.
Several mechanisms combine to give a fatigue life that is independent of ribbon width below 1.7 mm (65 mils). Above 1.7 mm width in‐plane flexure causes fatigue life to drop rapidly. No improvement from changed ribbon thickness is predicted.
Tread life appears to be better with ribbon than with cord, but the reason for this is not clear. Ribbon packing geometry gives superior nail penetration resistance.