Rubber composition for use in tires, and pneumatic tire

A rubber composition for a tire, comprising:

• a rubber component comprising a modified styrene butadiene rubber that contains a constitutional unit derived from a nitrogen-containing compound in a main chain;
• silica;
• and
• a diene rubber gel containing a hydroxy group and having a glass-transition temperature of −40 to −10° C., the diene rubber gel being contained in an amount of 10 to 30 parts by mass per 100 parts by mass of the rubber component,
• the nitrogen-containing compound being represented by the following formula:
• wherein R0 represents a hydrogen atom, a C1-C30 aliphatic hydrocarbon group, a C3-C30 alicyclic hydrocarbon group, or a C5-C30 aromatic hydrocarbon group;
• R1 and R2 are the same or different and each represent a hydrogen atom,
• provided that at least one of R1 and R2 is not a hydrogen atom;
• R3 represents a hydrogen atom or a C1-C4 hydrocarbon group;
• X represents a divalent saturated hydrocarbon group optionally containing nitrogen, oxygen, or sulfur, and optionally substituted with
• wherein Z represents a divalent saturated hydrocarbon group optionally containing nitrogen, oxygen, or sulfur;
• and R4 to R7 are the same or different and each represent a hydrogen atom, a C1-C30 aliphatic hydrocarbon group, a C3-C30 alicyclic hydrocarbon group, a C5-C30 aromatic hydrocarbon group, or a heterocyclic group having 3 to 30 ring member atoms.