Rubber composition for tire and studless tire

An object of the present invention is to provide a rubber composition for a tire, which can achieve well-balanced improvement in fuel economy, abrasion resistance, and performance on ice and snow, and a studless tire for a passenger vehicle using the rubber composition. The present invention relates to a rubber composition for a tire, including a rubber component and silica, wherein the rubber component contains a modified natural rubber with a phosphorus content of 200 ppm or less, and butadiene rubber, and the silica has a CTAB specific surface area of 180 m 2 /g or more and a BET specific surface area of 185 m 2 /g or more.