Push the probe down on the tire until it reaches the deepest part of the groove. Place the base on top of the tread. Make sure it's touching either side of the tread. Lift the gauge to better see ...

Replace the tire if the top of Abe's head becomes uncovered by any of the grooves. If your tires are only partially worn, find out how much. Stick a tread-depth gauge (about $5 at auto-parts ...

[John] found that a digital tire tread depth gauge can work well for this application. Many of these gauges use the same electronics as the cheap digital calipers, for which the serial protocol ...