TIRE SERVICE TECH WAS POSITIONING A 50 TON DUMP TRUCK TIRE WHEN THE TIRE FELL FROM THE BOOM CLAMP TRAPPING TECH BETWEEN TIRE AND BOOM TRUCK BED AND FRAME. MINOR DAMAGE TO THE BOOM TRUCK BUT FA TALLY INJURING THE TIRE TECH. THE AREA WAS AN OPEN FIELD AREA, WEATHER WAS CLEAR, AREA WAS DRY, DAYLIGHT HOURS.