Decoding the FMCSRs: Why history matters for CMV compliance
The key to truly understanding the Federal Motor Carrier Safety Regulations (FMCSRs) often lies in their history.
Today’s regulatory language was shaped by decades of debate and compromise, much of it documented in the Federal Register, the government's official daily newspaper. Knowing the backstory of a regulation can not only answer persistent “why” questions, but also help understand the meaning behind the words and, ultimately, how to comply.
Consider these four examples when it comes to commercial motor vehicle inspection and maintenance requirements in 49 CFR Part 396.
“1 year and for 6 months”
Originally, carriers were required to retain inspection and maintenance records for 3 years. In 1979, the Federal Register documented a shift, reducing the retention period to “a period of 1 year and for 6 months after the motor vehicle leaves the motor carrier’s control,” as currently stated in 49 CFR 396.3.
The lack of a comma in that phrase has caused confusion ever since. Are the records to be maintained for 6 months after a vehicle is disposed of, or 18 months?
Fortunately, that 1979 document has the answer, stating the current requirements in a much clearer way:
“The time period for retaining the inspection and maintenance records is being reduced from the current 3-year requirement to 1 year. Once the vehicle leaves the service of the carrier, the records need only be maintained for 6 months.”
“Preceding 12 Months”
Regulations for the periodic inspection in 396.17 require each vehicle to have been inspected “at least once during the preceding 12 months.” Does that mean the next inspection must be completed within 365 days of the last one, or that it must be completed before the end of the month, 1 year later, potentially allowing nearly 13 months between inspections?
The answer lies in a 1988 Federal Register when the rule was first adopted. It says the USDOT considered adding “365 days” to the rule but got pushback from the industry, which argued that “a day-specific requirement was too restrictive and inconsistent with most inspection program periods.”
As a result, the inspection sticker need only contain the month and year of the last inspection, and most enforcement agencies allow a grace period for the next inspection until the end of the month. However, completing each subsequent inspection within 365 days is highly recommended since that’s the common understanding of “12 months.”
Lubrication records
The regulations in 396.3 used to specify that lubrication records must be retained, but the rules no longer say that. So if today’s regulations only say you need to keep records of “inspection, repairs and maintenance,” does that include lubrication records?
The answer is yes, and it dates back to 1994 when the USDOT stated that “the lubrication record … is a maintenance record, [so] the requirement is redundant.”
Bottom line: lubrication is considered part of “maintenance” and therefore you must maintain all lubrication records for at least 12 months.
We need the tire size?
Many motor carriers are surprised that “tire size” is a required record in a vehicle file. It’s nestled among a list of vehicle details that must be retained, such as the make, serial number, and year. But why tire size?
Tire size used to be one of several tire details that carriers had to retain, including the number of tires and their load rating. The industry was questioning the need for such details as far back as the 1970s, leading the USDOT to remove some (but not all) of them in 1979, when it wrote in the July 2nd edition of the Federal Register:
“The suggestion that tire records are not needed has been carefully studied. Tire size has a direct bearing on the load-carrying capacity of a vehicle, but ply rating or load rating may not be needed. The load or ply rating will be dropped, but size of tires will be retained.”
Tire size may seem out of place in today’s vehicle files, but at least the government provided a safety-based justification — even if we must look back nearly 50 years to find it.
Key to remember: Regulatory language is never arbitrary. To truly understand why the regulations are worded the way they are, motor carriers must sometimes look beyond the text and understand the story behind the rule.














































