Method and device for classifying tires

A device for classifying a tire which comprises:

• (a) a radiation source for irradiating x-rays or .gamma.-rays on a first sidewall of a tire at a predetermined angle of inclination relative to the plane of the tire;
• (b) means for moving said tire relatively to said radiation source;
• (c) radiation detecting means provided to receive said rays penetrating a second sidewall of said tire, for detecting the intensity of x-rays or .gamma.-rays which have penetrated through said tire and having means for producing an output signal;
• (d) minimum point detecting means for detecting where said output signal of said radiation detecting means shows minimum values, to produce detection signals;
• (e) period detecting means for detecting from said detection signals of the minimum point detecting means periods of time during which said x-rays or .gamma.-rays separately penetrate through said first sidewall and said second sidewall;
• (f) maximum value measuring circuits for measuring two maximum values of said output signal of said radiation detecting means, said two maximum values occuring during said periods of time detected by said period detecting means, respectively;
• and (g) a comparison circuit for comparing said maximum values with each other, thereby to determine whether said tire is a tire with a white ribbon on a sidewall therefore or is a tire without a white ribbon.