PURPOSE: To reduce rolling resistance, by providing side rubber with a stress decreasing groove which extends toward base rubber near the part of the side rubber which is connected to tread rubber and by making the resilience of the base rubber higher than that of the other rubber sections.
CONSTITUTION: Base rubber 10 of relatively small thickness is provided just under the connection 9 of side rubber 6 with tread rubber 7 so that the base rubber 10 extends on both the side rubber 6 and the tread rubber 7 along the outside surfaces of a toroidal carcass 1 and a belt layer 3 and is overlapped with the side rubber 6 and tread rubber 7. The base rubber 10 has higher resilience than the side rubber 6 and tread rubber 7. The side rubber 6 is provided with a stress decreasing groove 11 which is located near the connection 9 and whose depth is oriented toward the base rubber 10.
SATOU AKIO
TAKUSAGAWA TAKASHI
IKEDA NOBUTADA
