Abstract: A system is disclosed for detecting potential defects as evidenced by surface irregularities in the sidewalls of a tire to be tested. A test is performed on a "uniformity machine" programmed to run standard tire tests. The system preferably utilizes a pair of oppositely disposed non-contact probes, means for distinguishing between `noise` and a desired signal, means for analyzing and identifying the signal, means for determining whether the identified signal falls within a preselected range, and means for identifying a tire having acceptable or unacceptable bumps and/or depressions. A tire is deemed acceptable when it qualifies within preselected limits for bumps and/or depressions, and unacceptable if it does not so qualify.