TREAD THICKNESS MEASURING METHOD

The invention provides a tread thickness measuring method for accurately measuring the tread thickness from a belt surface located in an outermost position in a tire to the tread surface by an ultrasonic measurement irrespective of the material of the belt. The method includes the steps of spraying the same liquid as the liquid pooled in a tank on the tread surface of the tire under inspection before immersing the tread surface in the liquid in the tank and measuring the depth of the belt located in the outermost position in the tire by emitting ultrasonic waves to the tread surface immersed in the liquid in the tank and receiving the reflected waves.