TIRE WEAR STATE ESTIMATION APPARATUS

An estimation apparatus includes a rotation speed acquisition unit, a driving force acquisition unit, a slip ratio calculation unit, a slope calculation unit, and an estimation unit. The rotation speed acquisition unit sequentially acquires rotation speeds of the tires. The driving force acquisition unit sequentially acquires a driving force of the vehicle. The slip ratio calculation unit calculates a slip ratio based on the sequentially-acquired rotation speeds of the tires. The slope calculation unit calculates the slope of the slip ratio with respect to the driving force based on a large number of data sets of the slip ratio and the driving force, as a regression coefficient representing a linear relationship between the slip ratio and the driving force. The estimation unit estimates the wear state of the tires based on the slope.