Sughrue, Rothwell, Mion, Zinn and Macpeak
Heavy duty pneumatic radial tire
 A heavy duty pneumatic radial tire having tread patterns divided into a central zone and peripheral zones by two main continuous zigzag grooves spaced apart a distance 25-38% of the overall width of the tread and having a main groove oblique or zigzag angle of 55-78.degree. relative to a radial plane of the tire. Each of the peripheral zones is divided into the form of arrow feathers by traverse grooves having walls tilted through at least 20% of the depth of the traverse groove at an angle within 20-40.degree. to a center line of the traverse groove. The ratio of total areas of the central zone to those of one of the peripheral zones is 1:1.0 to 1:1.5, and the ratio of the total areas of inner and outer peripheral blocks in the peripheral zones divided by a continuous zigzag groove substantially parallel with the main grooves is 1:1.5 to 1:2.5, thereby greatly mitigating ununiform wear at the shoulders of the tread, heal-and-tow wear between front and rear edges of blocks defined by the grooves in the pattern, and railway wear at the edges of the blocks in opposition to the grooves. 
Bridgestone Tire Company Limited
B B B B Y B B
B60C B60C B60C B60C Y10S B60C B60C
inventional inventional inventional inventional additional additional inventional
Hiroshi Hiroyoshi Shigeo Shigeta
Ogawa Takigawa Watanabe Aoki