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; silica; and a silane coupling agent, wherein 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 is a copolymer comprising units A represented by formula (1) and units B represented by formula (2), and the proportion of the units B is 1 to 70 mol % of the total molar amount of the units A and the units B.