Truck Tire Tread Depth and Condition: Steer, Drive and Trailer

Tread depth is measured with a tread depth gauge in the tread's major grooves, at more than one point on each tire, and recorded by position. A tire's condition is more than its tread depth. How it is wearing, and any damage to the tread, sidewall or bead, belong in the same record. This page covers how to measure and what to look at. It does not state a tread depth limit.

How is truck tire tread depth measured?

Read a tread depth gauge in a major tread groove, the main circumferential grooves that run around the tire. Keep the gauge off wear bars, tie bars and other features molded into the groove floor. They sit above the groove floor and give a falsely shallow reading. Take readings at several points across the tread and around the tire. A single reading can miss wear that is uneven. Record the readings by position, and note the lowest for each tire, so the next visit can compare. Record each dual tire on its own.

The tire manufacturer's care guidance says where to place the gauge for its tread designs.

What about steer tire tread depth?

Yes, steer tires have their own minimum. The federal rule for tires on vehicles in operation, 49 CFR 393.75 (Tires), sets one tread depth for tires on the front wheels of a bus, truck or truck tractor and another for tires in other positions. It also covers tire damage, tire load and cold inflation pressure. This page does not restate its values. Read the section on eCFR.

• The annual inspection standard for tires is on Appendix A inspection standards.
• What roadside inspectors cite is on FMCSA out-of-service checks.
• Many customers pull tires at their own removal depth, set above any regulatory minimum. Ask the customer for it, and record the depth that was measured, not just whether the tire was kept or replaced.

What does irregular tire wear look like?

Irregular wear is wear that is not even across the tread or around the tire. The common patterns have names a technician will recognize:

• shoulder wear: one or both shoulders wearing faster than the center;
• center wear: the center wearing faster than the shoulders;
• cupping or scalloping: dips worn into the tread at intervals around the tire;
• feather wear: tread ribs worn to a sharp edge on one side;
• flat spots: a patch worn flat at one place on the circumference;
• diagonal wear: worn patches running at an angle across the tread.

These are signs to record, with the position and how far along the wear is. What causes each pattern, and what to check on the vehicle when one appears, is in the tire manufacturer's guidance. One example is Michelin's irregular tire wear page. The industry reference is TMC RP 216, Radial Tire Conditions Analysis Guide, from the Technology & Maintenance Council of the American Trucking Associations. Use the current revision. This page does not say what caused wear on any particular tire.

What sidewall and casing damage should be recorded?

Look at the whole tire, not just the tread, and record what you find:

• cuts, snags and punctures in the tread or sidewall, and whether they reach the cord;
• bulges, which can point to damage inside the casing;
• exposed cord or belt material;
• separation of the tread or sidewall;
• cracking of the rubber;
• bead damage, at the edge of the tire that seats on the wheel;
• objects caught between duals;
• duals that do not match each other in size or wear.

Whether a damaged tire can be repaired, retreaded or must be scrapped is a decision for the tire manufacturer's guidance and a qualified tire repair or retread provider. Record what was found and what was done.

Retreads

Many drive and trailer tires are retreaded. The original casing is reused, with new tread applied. A retreaded tire carries markings that identify the retread, and the casing still carries its original DOT code. Record that a tire is a retread when it is one.

What the record should show

For each tire, by position: the tread depth as measured, the wear pattern if any, damage found, and whether the tire was left in service, repaired or replaced. See recording a tire and wheel service.

Log the work in Blue Collar Parts

A technician who measures tread or inspects tires can log the work in Blue Collar Parts and send the record to their customer, who confirms it. Learn what Blue Collar Parts is.

This page describes tire condition checks in general terms. It is not a service manual, does not state regulatory limits, and does not establish regulatory compliance. Use the tire manufacturer's current documentation and the current eCFR text for specifications and requirements.