ASTM F421-15

5.1 The groove (void) depth affects the tire’s ability to develop tractive forces in various operating environments. Groove (void) depth also defines the state of wear of a tire and is used in the determination of the rate of wear.

1.1 This test method describes standard procedures for measuring the groove and void depth in passenger car tires.

1.2 Any mechanical, optical, or electronic device capable of measuring groove (void) depth can be used, but only the contact methodology is described here. Noncontact methodology is beyond the scope of this test method.

1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.