Tire testing apparatus

A tire testing apparatus of drum type, comprising:

• a drum having, on a circumferential outer surface thereof, a sensor for measuring a ground contact force of a tire and a transparent portion;
• an image capturing device for capturing, from inside of the drum and through the transparent portion, an image of the ground contact surface of the tire;
• a ground contact force measurement processing unit for measuring a ground contact force of the tire in planner contact with the sensor;
• a ground contact surface image capture processing unit for capturing an image of the ground contact surface by the image capturing device when the tire comes into planner contact with the transparent portion;
• and
• a slip amount calculation processing unit which calculates a slip amount based on a displacement of a corresponding location which corresponds to a ground contact surface of a tire for which a measurement is made by the ground contact force measurement processing unit and which is in an image information of the ground contact surface of the tire under a different load.