Tire tread depth legal checker for trucks

This tire tread depth legal checker returns whether each tire position meets the federal minimum tread depth for commercial vehicles, and flags tires close to the limit.

Tires are one of the most common reasons trucks are cited at roadside, and tread depth is the easiest tire problem to catch before it becomes one. A tread gauge costs a few dollars. A steer tire violation, or worse a steer tire failure, costs a lot more.

How it works

Enter the lowest reading for each position in 32nds of an inch. The checker compares each with the federal minimum:

• Steer tires: at least 4/32 inch in a major tread groove
• All other positions: at least 2/32 inch in a major tread groove

It flags any tire within 1/32 inch of the minimum as close to the limit. Switch Units to see millimeters.

Source: 49 CFR 393.75, checked October 2026

A worked example

A driver measures 5/32 on the left steer tire, 4/32 on the right steer, 3/32 as the lowest drive reading and 6/32 on the trailer. All four are legal. But the right steer is exactly at the minimum and the drive tires are 1/32 from theirs. One more week of wear could put the truck out of compliance, and wet traction at that depth is already poor. The sensible move is to plan replacement now, at a shop and time you choose.

Semi truck tire tread depth chart in practice

New truck tires often start somewhere between the mid teens and the high twenties in 32nds, depending on the tire and position; drive tires with deep lugs start deeper than steer tires. The legal minimum is the floor, not the target. Many owners plan steer replacement well above 4/32 and pull drive and trailer tires before they reach 2/32, especially before winter.

How to measure

• Use a tread depth gauge, pressed into a major groove.
• Avoid the wear indicator bars molded into the groove.
• Check at several points around the tire and across the width.
• Record the lowest reading for each tire.
• Check inflation at the same time with a calibrated gauge, cold.

Uneven wear is a clue. Wear on one shoulder can point to alignment, cupping can point to balance or suspension, and center wear can point to over-inflation. Our guide to commercial truck tire tread depth covers wear patterns and what they mean, and the guide to truck tire repair covers which damage can be repaired and which cannot.

More than tread

A tire can fail inspection with plenty of tread: exposed cords, bulges, cuts, a flat or audible leak, or a tire touching another part of the truck. Steer tires have extra rules, including limits on regrooved and recapped tires on some vehicles. Check the whole tire, not just the depth.

Before winter runs

Several western states post chain controls in winter, and deep tread matters as much as chains on ice and snow. The chain law checker by state links to each state's official source.

What tires cost per mile

Tires are a cost of every mile. The tire cost per mile calculator works out yours from what a set costs and how long it lasts, so you can put it in your rate.

Matching duals

Dual tires should be closely matched in size and tread depth. When one tire in a dual pair is much more worn than the other, the taller tire carries more of the load and wears or overheats faster, and the pair scrubs as it rolls. Check the depth of both tires in each dual set and replace or rotate them so they stay close. Your tire supplier or the tire maker can tell you how close the match should be for your tires.

Rotate and record

Write down the readings each time you check, with the date and odometer. A log shows how fast each position wears, which tells you when replacement is coming and whether something such as alignment is eating tires. It also helps you plan the shop visit before a tire reaches the limit on a load.

Where we fit

We are a dispatch desk, not a tire shop. When your truck is ready, we find and negotiate loads, you say yes, counter or no, and the broker sends the rate confirmation to you to sign. For one-truck operations, the owner-operators page lays out the details.