The present invention provides a rubber composition for base tread having
reduced heat build-up characteristics and excellent reinforcing property,
and a pneumatic tire using the rubber composition for the base tread. The
rubber composition for base tread of the present invention comprises 30
to 40 parts by weight of carbon black having iodine adsorption amount of
at least 115 mg/g, 5 to 10 parts by weight of silica and 1.2 to 2.2 parts
by weight of sulfur based on 100 parts by weight of a rubber component,
wherein the total amount of the carbon black and the silica is at most 45
parts by weight. The pneumatic tire of the present invention is obtained
by using 20 to 80% by volume of a base tread based on the total volume of
a tread comprising the rubber composition.