It is an object of the present invention to provide a tire rubber composition excellent in performances such as silica dispersibility and processability. The present invention relates to a tire rubber composition, comprising: a rubber component that contains an epoxidized natural rubber; silica; and a silane coupling agent, wherein the amount of the epoxidized natural rubber in 100% by mass of the rubber component is 15% by mass or more, the silica has a CTAB specific surface area of 180 m2/g or more and a BET specific surface area of 185 m2/g or more, and the silane coupling agent contains a mercapto group.