Truck Tire Rules: Tread Depth, Retreads and Pressure
Federal rules set the minimum tread depth for truck tires: at least 4/32 of an inch on the front wheels of a bus, truck or truck tractor, and at least 2/32 of an inch on all other tires (49 CFR 393.75). No vehicle may run a tire that is flat or leaking, has ply or belt showing, or has tread or sidewall separation. A bus may not run retreads on the front, and a truck may not run a large regrooved tire there.
Facts checked October 17, 2026
Key Points
- Front wheels of a bus, truck or truck tractor need a tread groove depth of at least 4/32 of an inch. Measure at any point on a major tread groove (49 CFR 393.75(b))
- Every other tire needs at least 2/32 of an inch in a major tread groove. Do not measure where tie bars, humps or fillets are (49 CFR 393.75(b) and (c))
- No vehicle may run a tire with body ply or belt showing through the tread or sidewall, with tread or sidewall separation, that is flat or has an audible leak, or that has a cut deep enough to show the ply or belt (49 CFR 393.75(a))
- A bus may not run regrooved, recapped or retreaded tires on the front wheels. A truck or truck tractor may not run a regrooved tire with a load capacity of 4,920 pounds or more on the front wheels (49 CFR 393.75(d) and (e))
- A tire may not carry more weight than its sidewall marking, unless a state special permit applies and the vehicle runs slower, never over 50 mph (49 CFR 393.75(g))
- A tire may not run with a cold inflation pressure below what is specified for the load. Hot tires are corrected with the table in the rule (49 CFR 393.75(i))
- A tire labeled for 55 mph or less may not be run faster than its rated limit (49 CFR 393.75(f))
Tire limits for commercial motor vehicles (49 CFR 393.75)
| Tire or situation | What the rule says | Where | |
|---|---|---|---|
| Front wheels of a bus, truck or truck tractor | Tread groove depth at least 4/32 inch at any point on a major tread groove | 393.75(b) | |
| All other tires | Tread groove depth at least 2/32 inch in a major tread groove | 393.75(c) | |
| Any tire, any wheel | No ply or belt showing, no separation, not flat or leaking, no cut that shows ply or belt | 393.75(a) | |
| Front wheels of a bus | No regrooved, recapped or retreaded tires | 393.75(d) | |
| Front wheels of a truck or truck tractor | No regrooved tire with a load capacity of 4,920 pounds or more | 393.75(e) | |
| Speed-restricted tire labeled 55 mph or less | Do not exceed the rated speed | 393.75(f) | |
| Tire load | No more than the sidewall marking, unless a state special permit applies and speed stays at 50 mph or less | 393.75(g) | |
| Cold inflation pressure | Not less than specified for the load being carried | 393.75(i) |
How much tread must a truck tire have?
The front wheels of a bus, truck or truck tractor need a tread groove pattern depth of at least 4/32 of an inch. You can measure at any point on a major tread groove (49 CFR 393.75(b)). Every other tire needs at least 2/32 of an inch, measured in a major tread groove (49 CFR 393.75(c)). That includes the drive tires and the trailer tires. For both measurements, do not measure where tie bars, humps or fillets are. A tread depth gauge in 32nds of an inch reads the number the rule uses.
What tire damage is not allowed?
No motor vehicle may be operated on a tire that has any of four problems (49 CFR 393.75(a)). The first is body ply or belt material showing through the tread or sidewall. The second is any tread or sidewall separation. The third is being flat or having an audible leak. The fourth is a cut deep enough to show the ply or belt material. Any one of these is enough. The rule has no tread depth test for them, so a tire with plenty of tread can still fail.
Can you run retreads or regrooved tires on the steer axle?
It depends on the vehicle. A bus may not run regrooved, recapped or retreaded tires on its front wheels (49 CFR 393.75(d)). A truck or truck tractor may not run a regrooved tire on its front wheels if the tire has a load carrying capacity of 4,920 pounds (2,232 kg) or more (49 CFR 393.75(e)). This section does not bar a retreaded or recapped tire on the front wheels of a truck or tractor. A carrier, a tire maker or a state may have stricter rules, so check them too.
What about overloaded and speed-restricted tires?
A motor vehicle may not run tires that carry more weight than the sidewall marking. If a tire has no marking, the limit is the weight in the publications FMVSS 119 lists. The one exception is a vehicle running under a special permit from the state, at a reduced speed that makes up for the extra load. That speed may never go over 50 mph (49 CFR 393.75(g)). A tire labeled for a top speed of 55 mph or less may not be driven faster than that (49 CFR 393.75(f)). In a final rule effective March 23, 2026, FMCSA said these rules do not require manufacturers to add load markings to tires (49 CFR 393.75(j)).
What tire pressure does the rule require?
No vehicle may run on a tire with a cold inflation pressure lower than what is specified for the load it carries (49 CFR 393.75(i)). Tires heat up on the road, and the rule has a way to correct for that. If the tire pressure rose because the vehicle was recently driven, subtract the build-up in the rule's table from the pressure you measured to estimate the cold pressure. For a vehicle that averaged 41 to 55 mph over the last hour, the table says 5 psi for tires with a maximum load rating of 4,000 pounds or less, and 15 psi for tires rated over 4,000 pounds. The rule does not give one pressure number for all tires, because it depends on the tire and the load.
Related Free Tools
Annual DOT Inspection Checklist
Every item from the federal minimum periodic inspection standards as a checklist, with your next due date and what the report must show.
Tire Cost Analyzer
Compare up to 2 tire options by true cost per mile, including fuel savings and retreads.
Pre-Trip / Post-Trip DVIR Checklist
A 49 CFR 396.11 compliant Driver Vehicle Inspection Report with defect tracking.
Frequently Asked Questions
What is the minimum tread depth for semi truck tires?+
4/32 of an inch on the front wheels of a bus, truck or truck tractor, and 2/32 of an inch on all other tires. Measure in a major tread groove, not where tie bars, humps or fillets are (49 CFR 393.75(b) and (c)).
What is the minimum tread depth for steer tires?+
At least 4/32 of an inch, measured at any point on a major tread groove (49 CFR 393.75(b)).
What is the minimum tread depth for drive and trailer tires?+
At least 2/32 of an inch in a major tread groove (49 CFR 393.75(c)). A tire may still fail for damage, a leak or low pressure even if the tread is deeper than that.
Can you run retreads on steer tires?+
Not on a bus. A bus may not run regrooved, recapped or retreaded tires on the front wheels. On a truck or truck tractor, the federal rule bars only a regrooved tire with a load capacity of 4,920 pounds or more on the front wheels (49 CFR 393.75(d) and (e)). Check your carrier's policy and state rules.
Can you regroove steer tires?+
A truck or truck tractor may not run a regrooved tire with a load capacity of 4,920 pounds or more on its front wheels (49 CFR 393.75(e)). A bus may not run any regrooved tire on its front wheels.
Where does DOT measure tread depth?+
In a major tread groove. For the front tires, at any point on a major tread groove. The rule says not to measure where tie bars, humps or fillets are (49 CFR 393.75(b) and (c)).
Does the DOT set a minimum tire pressure?+
It sets no single number. A vehicle may not run on a tire with a cold inflation pressure less than the pressure specified for the load being carried. If the tire is hot, subtract the build-up from the rule's table to estimate cold pressure (49 CFR 393.75(i)).
Is a tire with a nail leak legal to run?+
No, if the tire is flat or has an audible leak (49 CFR 393.75(a)(3)). A tire that has lost air also may fall below the cold inflation pressure the rule requires.
Do tires have to show a load rating on the sidewall?+
A tire may not carry more than the weight marked on its sidewall or, with no marking, the weight in the FMVSS 119 publications. FMCSA's 2026 final rule clarified that the FMCSRs do not require manufacturers to add load markings to tires (49 CFR 393.75(g) and (j)).
More federal trucking rules
- Hours of Service Rules for Truck Drivers
- ELD Mandate: Who Needs an ELD
- DOT Roadside Inspection Levels Explained
- DOT Drug and Alcohol Testing Rules
- Driver Qualification File Requirements
- DVIR and Vehicle Maintenance Rules
- New Entrant Safety Audit Requirements
- Hours of Service Exceptions and Exemptions
- Motor Carrier Insurance Requirements
- CDL Classes, Endorsements and ELDT Training
- DOT Physical and Medical Card Requirements
- Drug and Alcohol Clearinghouse Requirements
- Cargo Securement Rules for Trucks
- Hazmat Basics for Truck Drivers and Carriers
- USDOT Number and Biennial Update Requirements
- Safety Ratings, Compliance Reviews and DataQs
- Federal Truck Size and Weight Limits
- California Clean Truck Check (HD I/M)
- Truth-in-Leasing Rules for Owner-Operators
- Form 2290 Heavy Highway Vehicle Use Tax
- Truck Driver Phone, Texting and Seat Belt Rules
- Railroad Crossing Rules for Truck Drivers
- Truck Emergency Equipment and Warning Triangle Rules
- Truck Windshield, Dash Cam and Mirror Rules
- CDL Disqualification: Major and Serious Offenses
- Trailer Reflective Tape (Conspicuity) Rules
- Truck Brake Rules: Pushrod Stroke, Lining Thickness and ABS
- Driver Conduct Rules: Alcohol, Drugs, Fatigue, Passengers and Pre-Trip Checks
- English Language Proficiency for Truck Drivers: The 391.11(b)(2) Rule
- Weigh Station Rules: Who Must Stop and What Happens If You Skip
- Truck Lighting Rules: Required Lamps and Reflectors (49 CFR 393)
- Driver Road Test Rules: The Company Road Test and Certificate (49 CFR 391.31)
Related terms and pages
Sources
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This is a plain-language summary for reference, not legal advice. Check the official rule text before you rely on any detail. Ask a compliance professional about your own operation.