Truck Tires: Rules & Regulations

Truck Tires: Rules & Regulations

Wealth of government regs impact truck tires, but can dealers help meet requirements?

There are several government regulatory programs that directly affect truck tires and are important for dealers and fleets to understand.

The Code of Federal Regulations (CFR) 393.75 describes eight specific parts involving truck tires.
The Commercial Vehicle Safety Alliance (CVSA) is comprised of the law enforcement personnel who inspect commercial vehicles on our nation’s highways. CVSA publishes an annual North American Standard Out-of-Service Criteria manual, which identifies the common violations that render a commercial truck unqualified to drive or put out-of-service. Commercial truck tire issues that make up potential violations are detailed in the manual.

SmartWay is another government program. This one falls under the Environmental Protection Agency and has an impact on truck tires when it comes to fuel economy and reducing greenhouse gas emissions.
Compliance, Safety, & Accountability – better known as CSA – is the fourth government program that impacts truck tires. CSA is administered by the Federal Motor Carrier Safety Administration (FMCSA) under authority of the Department of Transportation.

With that introduction out of the way, let’s look at each in detail.

CFR 393.75
“No motor vehicle shall be operated on any tire” that:
• Has body-ply or belt material exposed through the tread or sidewall
• Has any tread or sidewall
• Is flat or has an audible air leak
• Has a cut to the extent that the body-ply or belt material is exposed

Parts B and C describe the minimum tread depth allowed. The measurement must be done in a major groove but should not be made where there are stone ejectors, tie bars and/or humps. The minimum tread depth for steer tires is 4/32-inch, and 2/32-inch for any other wheel position.

Part D only applies for busses and does not allow retreads or regrooved tires to be run on the steer or front tires. This is the only regulation that limits on what axle position retreaded tires can be run.

Regrooved tires, which are not very popular and are used primarily in city bus tires, are addressed in Part E. If the tire load capacity is equal to or greater than 4,920 pounds, then a regrooved tire can’t be used on the steer axle of a truck or tractor.

Parts F and G are the rules governing tire load restrictions. Part F is for all motor vehicles except for those trucks that are hauling manufactured homes, which are detailed in Part G. Motor vehicles are not allowed to be operated with tires that carry a weight greater than that marked on the tire sidewall. The only exceptions are if you have a special permit issued by the state or you are operating the vehicle at a reduced speed. Tire load-inflation tables, which take into account tire being run at low speeds, are published annually by the Tire & Rim Association (

Part G allows for an 18% tire overload when hauling manufactured homes. The last section, Part H, states that no motor vehicle can be operated at a cold tire inflation pressure less than specified for the specific load. If the tire is hot when it is checked, then an additional 15 psi greater than the cold pressure listed on the sidewall is allowed.

On April 1 every year, CVSA issues their updated out-of service criteria. Their rules are based on CFR 393.75, but with a few additional specifics to make it easier for inspectors during an on-highway vehicle inspection.

CVSA uses the same 4/32-inch and 2/32-inch tread depth guideline as stated in CFR 393.75. When it comes to bulges potentially related to a tread or sidewall separation, they allow a bulge up to 3/8-inch inch in height. If a tire has an air leak that can be easily heard or felt, the vehicle would be put out-of-service. It would also be put out-of-service if the actual inflation pressure was 50% or less of what is marked on the tire sidewall.

The CVSA guidelines also state that the inspector is to measure the actual tire inflation pressure only if there is evidence the tire is underinflated. This has always been an issue with fleets since it is almost impossible to tell if a radial truck tire has low tire pressure just by looking at the tire.

If a motor vehicle is carrying passengers, then retreaded or regrooved tires are not allowed on the steer axle.

The CVSA manual can be downloaded and purchased at

SmartWay is a unique collaboration between freight shippers, fleets and logistics companies to voluntarily achieve improved fuel efficiency and reduced emissions from freight transport (
Tires, specifically so-called fuel-efficient tires, play a major role in the EPA-administered program.

SmartWay publishes a list of new tires and retreads that are considered “verified” technology that improves vehicle fuel economy and reduces greenhouse gas emissions to help the environment. To make this verified list, a tire must meet a minimum rolling resistance criteria when run on a laboratory dynamometer.

SmartWay is a voluntary program except in the state of California. In California, a fleet must run only SmartWay fuel-efficient verified tires. This is mandated by the California Air Research Board (CARB) and the details on this program, which includes a few exemptions for older vehicles, can be found online.

Many fleets prefer to use fuel-efficient tires recommended by the SmartWay program since they not only save money and help the environment, but they are able to use the SmartWay marketing logo with their customers to let everyone know they are doing their part by being good corporate citizens.

CSA was implemented in 2010 to improve commercial vehicle safety on the nation’s roads. Brakes, lights and tires are the primary focus when vehicles are inspected.

This program penalizes with a “score” for both the fleet and the driver as the result of a live vehicle inspection. Tires can either receive 3 or 8 points depending on the severity of their operating condition. The 8-point conditions include running a tire below the legal tread depth limit and having exposed cords or wire. It also includes running on a flat tire.

By definition, a flat tire is considered any tire with an inflation pressure that is measured to be 50% or less of what is stamped on the tire sidewall. If even one tire has an 8 pointer, then the vehicle is considered out-of-service and would require a roadside service call. Drivers are not even allowed to drive to the next truck stop to get the tire repaired or replaced.

A 3-point penalty is assigned to tires that are “underinflated.” The problem is that CSA does not offer a definition of “underinflated.” A zealous inspector could decide that underinflation by 5 psi or 10 psi is a safety issue and write a citation.

Dealers are not behind the wheel when these inspections occur, but they can help fleet customers by instilling a consistent inspection and inflation program, even making sure to teach drivers the proper way to conduct their own on-road checks.

Understanding all the rules and regulations when it comes to commercial truck tires will make every tire dealer a valuable partner to their customers.  

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