A tire defect tester and a method of operation are disclosed. In one aspect, the tire defect tester includes a first electrode arranged to direct energy toward a tire, and a second electrode arranged on an opposite side of the tire from the first electrode to receive energy passing through the tire from the first electrode. The tire defect tester further includes an energy sensor electrically connected to the second electrode and a fault indicator circuit responsive to the energy sensor and configured to indicate the presence of a flaw upon energy above a threshold level being sensed at the second electrode.