Car Tire Size / Tire accessories / Tread gauges
Tread depth gauges
A tread depth gauge tells you how much tread is left, in 32nds of an inch. It takes a few seconds and says when your tires need replacing.
- NHTSA recommends replacing tires at
- 2/32 of an inch
- Better for rain and snow
- 4/32 of an inch or more
What to check before you buy
- Measure in several grooves, inside, middle and outside. Uneven wear points to alignment or pressure.
- No gauge at hand: the penny test. Lincoln's head down in a groove: if you see all of his head, there is 2/32 of an inch or less left.
- The small bars across the grooves are wear indicators: tread level with them is worn out.
Tread depth gauges listed on eBay
Sources: Ford Support, "Why does tread wear matter on my Ford?" (ford.com), citing NHTSA, read October 14, 2026.