Tire Inflation Petition

In January 2014, the American Trucking Association (ATA) filed a petition with the Federal Motor Carrier Safety Administration (FMCSA), objecting to 2012 federal regulations governing tire inflation for motor carrier vehicles. The ATA requested the removal of certain language in the regulation, claiming confusing guidelines for determining appropriate tire pressure led to unnecessary 3-point violation citations. Now, over three and a half years later, FMCSA has ruled that the regulations will stand as written.

However, the agency has made some concessions. The FMCSA plans to work with the Commercial Vehicle Safety Alliance (CVSA) to find some middle ground when it comes to enforcing the rule.

The Problem with Current Truck Tire Regulations

No one is arguing that neglecting truck tires is justifiable. Ask any driver, and they will tell you that checking tires for damage and underinflation is an important part of both pre-and post-trip inspections. Improperly inflated tires impact fuel mileage, cutting into the profit margins of both fleets and independent owner-operators. The road is harder on underinflated tires, too, significantly reducing the life of the tire. A good driver knows that using a tire gauge is the only accurate way to measure tire pressure and keep his or her wheels in good condition.

Defining the Issue

The major problem with current regulations is the difference between how drivers and roadside inspectors determine the appropriate tire pressure. Drivers typically use a load-based standard to determine ideal tire pressure. However, pressure requirements change every time a driver drops one load and hooks a new one. With hours of service (HOS) regulations limiting the amount of time spent on the road, it is virtually impossible to adjust tire inflation for every load hauled. For this reason, most companies set a standard tire pressure for drivers to maintain.

Roadside Inspection Standards

On the other hand, state inspectors must follow CFR § 393.75(h), which states:
“(1) No motor vehicle shall be operated on a tire with a cold inflation pressure less than that specified for the load being carried. (2) If the inflation pressure of the tire has been increased by heat because of the recent operation of the vehicle, the cold inflation pressure shall be estimated by subtracting the inflation buildup factor shown in Table 1 from the measured inflation pressure.”

In other words, roadside inspectors check the tire’s sidewall for the recommended pressure. If they suspect the tire is underinflated, they then deduct either five psi or 15 psi from the tire’s actual pressure to determine whether it is properly inflated.

Deduction amounts are based on the amount of time the vehicle has been in operation. Hot air expands, and the deductions account for the expansion the tire experiences due to friction while on the road.

Interpretive Guesswork

Unfortunately, state inspectors cannot determine how long the vehicle has been operating and often cannot weigh trailers. As a result, the guidelines intended to protect drivers and other highway traffic motorists are left mainly up to individual interpretation.

Those 30,000 citations would be an expensive annoyance except for one thing: each one is a 3-point violation for the driver. Points against a driver’s commercial driver’s license can add up quickly and take time to disappear. Too many violations and the driver may lose their job, even if they still have a valid license.

Not the Only Problem

Several other factors also cause issues with enforcing current regulations. A study by the ATA’s Technology and Maintenance Council (TMC) listed several reasons that developing a fair and simple way to measure tire inflation is practically impossible.

  1. Ambient temperature, tire construction, and operating time all play a part in how much a tire expands while on the road. Simplifying deductions for heat expansions to 5 or 15 psi does not make sense.
  2. Since the inspectors do not know how long the vehicle has been on the road, deducting 15 psi per tire is unfair to vehicles that have been operating for a short time or sitting while waiting for an inspection.
  3. Empty or light loads do not require the same tire pressure as a full or heavy load. For example, tires with a maximum pressure of 110 psi can safely operate at 75 psi with a light load. However, deducting 15 psi per tire means the recorded pressure would only be 60 psi, resulting in a violation.
  4. The issues outlined in point 3 result in drivers with light loads being penalized unfairly.
  5. Steer axle tires often have a higher load range because they carry a consistent amount of weight. However, these tires are often retreaded and used under rear axles. The recycled tires can safely operate at lower pressures with this type of use. However, to a roadside inspector, the same tire appears grossly underinflated.

Ultimately, the FMCSA’s view seems to be that taking the guesswork out of enforcing the regulations will address the concerns the ATA has raised. The agency believes that working with the Commercial Safety Vehicle Alliance’s (CSVA) Vehicle Committee to train inspection officials and establish regulatory guidelines.

However, according to TMC’s executive director Robert Braswell, CSVA’s official inspector guidelines should prohibit roadside violations for under-inflated tires. “…inspector guidelines [state] that ‘393.75(h) should not be written for an under-inflated tire. A violation of 393.75(f) should only be written when the opportunity to weigh a vehicle is present,” he said. Additionally, the weight on the tire must be higher than the load capacity printed on the tire’s sidewall.