Armstrong, Nikaido, Marmelstein, Kubovcik & Murray
Heavy duty pneumatic radial tire with improved steel cord belt
 A heavy duty pneumatic radial tire including between a tread and at least one carcass layer, at least two belt layers, wherein an outermost belt layer disposed most closely to the tread out of all belt layers comprises a steel cord which has a cord structure of 2+7 made of an element wire having a carbon content of 0.77 to 0.92% by weight and a diameter d of 0.28 to 0.40 mm and which has a tenacity at break of (1700.about.2050)d.sup.1.872 (kgf/cord) and a ratio of an elongation at break .epsilon. to P.L.E., .epsilon./P.L.E., of at least 30, and a coat rubber having a 50% modulus of 10 to 40 kg/cm.sup.2, and wherein the outermost belt layer has a thickness of at least 1.67 times the minor diameter but at greatest 1.79 times the major diameter, of the steel cord. 
The Yokohama Rubber Co., Ltd.
D D B B Y
D07B D07B B60C B60C Y10S
additional inventional inventional inventional additional
Eiji Susumu Yasuo
Igarashi Imamiya Suzuki