The total indicator reading, also known as TIR, is the difference between minimum and maximum readouts found when an indicator is run along the surface of a part while it is rotated along an axis. The TIR measures any discrepancy found in the planar, cylindrical, or contoured surface of a part. TIR is important for testing whether the flatness, circular, concentric, or any other shape for a part is maintained precisely or whether adjustments need to be made before the part can be used in a bigger machine. Back to entire glossary
