TIRE INTERNAL FAILURE DETERMINATION METHOD

A method for accurately determining internal failures, such as separations, of a tire without affecting tire behaviors. Radial acceleration signals of a tire during vehicular travel are detected by an acceleration sensor (11) attached to the inner surface of the tire at the axial center of the tread. A frequency analysis is performed on the radial acceleration signals to obtain a frequency spectrum. A band value X ab is calculated of a specific frequency band [f a , f b ] within the range of 100 Hz - 400 Hz, which includes the frequency of the second lowest peak of the peaks appearing in the frequency spectrum. Then a check is made to see whether or not the difference between this band value X ab and a predetermined band value Y ab of a normal tire exceeds a threshold value K. And when Y ab - X ab > K, it is determined that an internal failure, such as a separation, is present in the tire.