A loading device for a tire testing machine that is provided in a tire testing machine including a testing station provided with a spindle attached with a tire to be tested and feeds the tire from a predetermined standby position to a testing position where the center of the spindle matches the center of the tire in the testing station, the loading device for a tire testing machine comprising: a conveyor that conveys the tire from the standby position towards the testing position in a direction perpendicular to the axial direction of the tire; a positioning device adapted to position the tire to a position, in which a front end of the tire to be tested in the feeding direction matches a point separated from the spindle by a predetermined distance, as the standby position, wherein the positioning device includes a front end sensor that is provided at a specific position before the testing station so as to detect the arrival of the front end of the tire and a controller that controls an operation of the conveyor, and wherein the controller is adapted to operate the conveyor until the sensor detects the front end of the tire and to stop the tire at the standby position based on a time point when the sensor detects the front end of the tire, characterized in that the tire testing machine further comprises: a feeding distance calculating unit adapted to calculate the feeding distance as the distance in which the tire positioned to the standby position is fed towards the testing position based on an outer diameter of the tire and the distance from the standby position to a center position of the spindle and a conveying controller that operates the conveyor so as to feed the tire from the standby position towards the testing station by the feeding distance. a conveyor that conveys the tire from the standby position towards the testing position in a direction perpendicular to the axial direction of the tire; a positioning device adapted to position the tire to a position, in which a front end of the tire to be tested in the feeding direction matches a point separated from the spindle by a predetermined distance, as the standby position, wherein the positioning device includes a front end sensor that is provided at a specific position before the testing station so as to detect the arrival of the front end of the tire and a controller that controls an operation of the conveyor, and wherein the controller is adapted to operate the conveyor until the sensor detects the front end of the tire and to stop the tire at the standby position based on a time point when the sensor detects the front end of the tire, characterized in that the tire testing machine further comprises: a feeding distance calculating unit adapted to calculate the feeding distance as the distance in which the tire positioned to the standby position is fed towards the testing position based on an outer diameter of the tire and the distance from the standby position to a center position of the spindle and a conveying controller that operates the conveyor so as to feed the tire from the standby position towards the testing station by the feeding distance. a feeding distance calculating unit adapted to calculate the feeding distance as the distance in which the tire positioned to the standby position is fed towards the testing position based on an outer diameter of the tire and the distance from the standby position to a center position of the spindle and a conveying controller that operates the conveyor so as to feed the tire from the standby position towards the testing station by the feeding distance.