Abstract: Disclosed is a rubber composition having excellent low loss characteristics and capable of imparting a tire with wear resistance and fracture resistance. The rubber composition is obtained by blending a carbon black, which has a toluene coloring transmittance of not less than 90% while satisfying the following relation between the hydrogen emission rate (mass %) and the cetyltrimethylammonium bromide adsorption specific surface area (CTAB) (m2/g): the hydrogen emission rate >0.260?6.25×10?4×CTAB, into a modified natural rubber which is obtained by adding a polar group-containing monomer into a natural rubber latex for graft-polymerizing the polar group-containing monomer to a natural rubber molecule in the natural rubber latex, and then solidifying and drying the resulting product.

Abstract: This invention provides a rubber composition having an excellent low loss factor and capable of imparting a wear resistance and a fracture resistance to a tire, which is formed by compounding carbon black having a toluene coloring transmittance of not less than 90% and satisfying a relationship between hydrogen emission ratio (% by mass) and cetyltrimethylammonium bromide adsorption specific surface area (CTAB) (m2/g) of the following equation: Hydrogen emission ratio>0.260?6.25×10?4×CTAB into a modified natural rubber formed by adding a polar group-containing monomer to a natural rubber latex to graft-polymerize the polar group-containing monomer onto a natural rubber molecule in the natural rubber latex and then coagulating and drying.