| 主权项 |
1. A pneumatic tire having an under tread and a cap tread arranged on belt layers embedded in a tread portion, the under tread being formed by a rubber composition for an under tread;
the rubber composition for the under tread comprising: from 15 to 45 parts by weight of carbon black per 100 parts by weight of diene rubber, from 3 to 30 parts by weight of silica per 100 parts by weight of the diene rubber, and from 5 to 15% by weight, relative to the amount of the silica, of a silane coupling agent; the diene rubber comprising: from 70 to 90% by weight of natural rubber and/or isoprene rubber, and from 30 to 10% by weight of butadiene rubber and/or styrene butadiene rubber; a nitrogen adsorption specific surface area N2SA of the carbon black being from 35 to 85 m2/g and a DBP absorption number of the carbon black being from 105 to 200 mL/100 g; if an amount of sulfur contained in the rubber composition for the under tread per 100 parts by weight of the diene rubber is Y parts by weight and if an amount of sulfur contained in a rubber composition for coating that forms the belt layers per 100 p arts by weight of a rubber component is X parts by weight, a difference between the sulfur contents (β=X−Y) being 4.5 or less; and if a rubber hardness of the cap tread is A and if a rubber hardness of the under tread is B, a difference between the rubber hardnesses (α=A−B) being from 5 to 12. |
