DOT tire violations: what 49 CFR 393.75 says and how it counts on your CSA score

Every tire violation on a roadside inspection is cited under one federal rule, 49 CFR 393.75, and every one of them lands in the Vehicle Maintenance BASIC of your CSA record. This guide quotes the rule word for word, shows how FMCSA’s Safety Measurement System (SMS) weighs a tire violation, and sets out what a DataQs challenge can and cannot fix.

The rule, word for word

49 CFR 393.75(a): “No motor vehicle shall be operated on any tire that—

• (1) Has body ply or belt material exposed through the tread or sidewall,
• (2) Has any tread or sidewall separation,
• (3) Is flat or has an audible leak, or
• (4) Has a cut to the extent that the ply or belt material is exposed.”

Tread depth is in paragraphs (b) and (c):

• Front tires, 4/32 of an inch.“Any tire on the front wheels of a bus, truck, or truck tractor shall have a tread groove pattern depth of at least 4/32 of an inch when measured at any point on a major tread groove. The measurements shall not be made where tie bars, humps, or fillets are located.”
• All other tires, 2/32 of an inch.“Except as provided in paragraph (b) of this section, tires shall have a tread groove pattern depth of at least 2/32 of an inch when measured in a major tread groove. The measurement shall not be made where tie bars, humps or fillets are located.”

The rest of the section covers:

• (d) and (e): regrooved, recapped and retreaded tires on front wheels;
• (f): tires labelled with a maximum speed of 55 mph or less, run faster than their rating;
• (g) and (h): tires carrying more weight than their sidewall rating (with separate rules for manufactured homes);
• (i): inflation. “No motor vehicle shall be operated on a tire which has a cold inflation pressure less than that specified for the load being carried.” If the tire is hot from recent driving, the rule’s Table 1 has the cold pressure estimated by subtracting a heat buildup factor: after an average of 41–55 mph in the previous hour, 5 psi for tires rated 4,000 lbs or less and 15 psi for tires rated above 4,000 lbs.

Paragraph (j), added on 19 February 2026 (91 FR 7887), says the load rules in (g) and (h) do not require manufacturers to add markings to the sidewall.

The code on your report is not the rule

FMCSA’s public SMS data lists 45 different violation codes under 393.75, each with a short description. Those descriptions are labels from the inspection system. Some are worded more narrowly than the regulation, and some carry thresholds the regulation does not mention. Two examples from the current data:

• Code 39375A1TAORETA reads “has more than one ply exposed in the tread area exceeding 2 square inches.” The regulation it cites, 393.75(a)(1), covers “body ply or belt material exposed through the tread or sidewall.” Exposed belt material is a violation of the rule even though the label speaks of plies.
• Codes 39375A3TAOL and 39375A3TAOLTIS separate a leaking or under-inflated tire “not equipped” and “equipped” with ATIS (an automatic tire inflation system). Section 393.75 never mentions ATIS. Both codes carry the same severity weight of 8, so a correction that only swaps one code for the other fixes the record without changing the weight.

The lesson cuts both ways. A label that is narrower than the regulation is not, on its own, a reason the violation is wrong: the question a reviewer asks is whether the condition the officer recorded meets the CFR text. Read the regulation, then read what the officer wrote, and compare those two.

How a tire violation counts

• Which BASIC. All 45 tire codes are in the Vehicle Maintenance BASIC, which uses violations from vehicle inspections (Levels 1, 2, 5 and 6) in the past 24 months.
• Severity.Codes in FMCSA’s “Tires” group, such as exposed ply or belt, separation, flat or leaking, cuts, tread depth and speed rating, carry a severity weight of 8. Codes in the “Tire vs. Load” group, which covers weight over the tire’s load limit (including from under-inflation) and regrooved front tires, carry 3. One exception comes from a court result: a citation that ends in a conviction on a different charge drops to severity 1 (see your ticket was dismissed in court).
• Out of service. A violation that put the vehicle out of service gets 2 more. How out-of-service violations work: out-of-service violations and your CSA score.
• Same code, one count. When the same violation is cited more than once on one inspection, the SMS uses it only once. Different codes count separately, and the total severity on one inspection in one BASIC is capped at 30.
• Time weight. The severity is multiplied by 3 for a violation in the last 6 months, 2 from 6 to 12 months, and 1 from 12 to 24 months. After 24 months it no longer counts.

Worked example (a hypothetical inspection, arithmetic on the rules above).A flat tire cited as out-of-service under 39375A3 four months ago counts (8 + 2) × 3 = 30toward your Vehicle Maintenance measure. If the officer cited two flat tires under that same code on that inspection, it still counts 30, not 60. A flat tire (10) plus a front tire under 4/32 of an inch (8) on the same inspection counts 18 × 3 = 54. Thirteen months after the inspection the same pair counts 18 × 1 = 18. The measure divides these points by the time weight of all your relevant inspections, clean ones included; see what is a CSA score?

Before you challenge: what a reviewer can act on

1. Check the unit is yours. Match the VIN and plate on the report against your registrations and leases. A unit that belongs to another carrier is a different kind of request: an inspection on your record that isn’t yours.
2. Compare the report with itself.If the report cites the 4/32 front-tire rule, 393.75(b), for a tire it places on a trailer axle, where the rule is 2/32, and records a depth of 2/32 or more, or if the officer’s narrative describes a condition the cited regulation does not cover, the report contradicts its own violation. A report that simply records no measurement is different: the reviewer can ask the officer, so a missing detail is usually not enough.
3. Count the repeats. Because one code counts once per inspection, correcting one of three tires cited under the same code leaves the violation in place at full weight. Every instance has to be wrong, each for its own documented reason.
4. Know what a repair receipt proves. A receipt for a tire replaced after the inspection shows you fixed it. It does not show the tire met the rule at the roadside, so it does not contradict the report.
5. File it properly. A request that carries its own proof, attached on the first submission: how to dispute a DOT violation and file a DataQ.

If none of these applies and the report is accurate, a challenge will not remove the violation. It loses weight at 6 and 12 months and stops counting at 24.

Sources

• 49 CFR 393.75, Tires (eCFR, current to 7 October 2026; last amended 91 FR 7887, 19 February 2026): paragraphs (a) to (j) and Table 1, quoted above.
• FMCSA, Safety Measurement System (SMS) Methodology, Version 3.21 (methodology revised May 2026): Vehicle Maintenance BASIC, pp. 3-13 to 3-15 (applicable violations and relevant inspections, one cite per inspection, OOS weight of 2, cap of 30, time weights); Appendix B, Table B-10 (393.75B-OOS, 393.75C-OOS and 393.75F-SPEED at severity 8; 393.75G-LOAD and 393.75I1 at 3).
• FMCSA, “SMS Input – Violation” dataset, data.transportation.gov: the 45 violation codes beginning 39375, their descriptions, BASIC, violation group and severity weight, read 9 October 2026.