PURPOSE: To improve separation durability at the ends of a belt, and to reduce rolling resistance by constituting a tread reinforcement belt by laminating an extensible protective layer, nonextensible principal layers, and a nonextensible additional layer of a prescribed width, each of which has slantingly arranged cords and a specific breaking elongation, in this order from the radial-directional outside.
CONSTITUTION: A tread reinforcement belt 2 is made up of an outermost protective layer 11 consisting of at least one layer of extensible cord, a plurality of principal layers 10 consisting of nonextensible cords on the outside thereof, and an additional layer 12 consisting of a nonextensible cord on the inner side thereof. In the protective layer 11, a high-elongation cord whose breaking elongation is 4.5 to 8% is arranged so as to have an inclination of 20 to 30deg. to the equatorial plane. In the principal part 10, nonextensible cords are arranged so as to have an inclination of 20 to 30deg. to the equatorial plane. The additional layer 12 is constituted by arranging a nonextensible cord in the inclination of 0deg., and also is positioned in the range of 1/2 to 1/5 of the maximum width of the principal layer 10. By this constitution, durability can be improved, and rolling resistance can be reduced.
GOTO AKIHITO
NAKAMURA YOICHI
