Honda Motor Co., Ltd.

Sumitomo Rubber Industries Limited

Emiko Mogi

Tetsuya Mizone

Takuya Horiguchi

Toshikazu Kondo

Shinya Notomi

Takeshi Hotaka

Provided is a pneumatic tire capable of improving fuel efficiency, handling stability, and durability in a balanced manner. The present invention relates to a pneumatic tire, comprising a tread that includes a cap layer and a base layer, the cap layer and the base layer satisfying relationships represented by the following formulas (1) to (3):50/50&#x2266;&#x2266;90/10&#x2003;&#x2003;(1)wherein Vc is the volume of the cap layer and Vb is the volume of the base layer,0.65&#x2266;&#x3c;1.00&#x2003;&#x2003;(2), and1.30&#x2266;(tan &#x3b4;)/(tan &#x3b4;)&#x3c;2.40&#x2003;&#x2003;(3)wherein E*c and tan &#x3b4;c are the complex modulus and the loss tangent, respectively, of the cap layer at 30&#xb0; C., and E*b and tan &#x3b4;b are the complex modulus and the loss tangent, respectively, of the base layer at 30&#xb0; C.

Pneumatic tire

The rubber composites for tire treads include silica; carbon black; and oil constituents, wherein a ratio (A index) of silica contents, carbon black contents, and oil constituents contents is represented by A index=silica contents/(carbon black contents+silica contents+oil constituents contents)&#x2267;0.8; and a ratio (B index) of a complex elastic modulus E* at 30&#xb0; C. and a loss tangent tan &#x3b4; at 60&#xb0; C. is represented by B index=E*/tan &#x3b4;&#x2267;120.

Rubber composites for tire treads and tire

There are provided the tire motorfor increasing or decreasing the tire rotational frequency Nt while the tireis being rotated around the tire rotational shaft, the rotational frequency measuring meansfor measuring the tire rotational frequency Nt, the drum motorfor rotating the test drumaround the drum rotational shaftat the constant drum speed Vd, the speed meterfor measuring the drum speed Vd, the load applying meansfor pushing the tireagainst the test drumwith the tire load Fz, the radial force load cellfor measuring the tire load Fz, the tangential force load cellfor measuring the tangential force Fx that is exerted on the tire, and the recording means for recording the measurement result of each of the drum speed Vd, the tire rotational frequency Nt, the tangential force Fx and the tire load Fz in association with every measurement time point during increasing or decreasing the tire rotational frequency.

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Saitama, Japan

Emiko Mogi