ASTM F 421 - 15 Standard Test Method for Measuring Groove and Void Depth in Passenger Car Tires

Current edition approved June 1, 2015. Published August 2015. Originally approved in 1975. Last previous edition approved in 2013 as F421 – 07 (2013)ɛ1. — 4 p.
This test method describes standard procedures for measuring the groove and void depth in passenger car tires.
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.