Rerating Vehicle GVWR and GAWRs

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NTEA commonly receives questions on rerating commercial vehicle gross vehicle weight rating (GVWR) and gross axle weight ratings (GAWRs). The following information and resources can help provide a better understanding of the implications of changing these ratings.

Can a used vehicle be rerated?

No. Certification and ratings assignment apply only to new motor vehicles by the manufacturer(s) during the initial build process. Once a vehicle has been completed in the final stage and licensed and titled by an owner in a given U.S. state, or sold and delivered to a purchaser at the first retail level in a Canadian province or territory, the certification obligation ends, along with assignment of ratings. In a 2002 interpretation, National Highway Traffic Safety Administration (NHTSA) provided this response to the concept of rerating used vehicles.
National Highway Traffic Safety Administration (NHTSA) does not have regulations or provisions for certifying a used vehicle, the process in which ratings are assigned. Additionally, companies that change the original GVWR/GAWRs of a used vehicle may face serious liability concerns.

How are vehicle ratings determined (GVWR/GAWRs)?

GVWR and GAWRs are the maximum weights a new, completed vehicle and individual axles, respectively, can bear and meet regulatory compliance requirements, durability and OEM warranty objectives.
Only the OEM would know which components or limiting factors set these ratings, so it’s important to consult the chassis manufacturer to determine if rating changes are possible and to what extent on a new vehicle.

Can axles be added to increase GVWR?

It’s a common misconception that GVWR can, or must, always be the sum of the GAWR values.
Even though the chassis may have more axles than it did originally from the factory, it does not mean it’s otherwise able to meet all brake system performance requirements at a higher GVWR. Warranty coverage can also be affected by these changes.
OEM incomplete vehicle documents (IVDs) often contain prohibitive language for changing GVWR, preventing the intermediate-, final- and/or altered-stage manufacturer from using OEM IVD guidance as a basis to certify the vehicle.
The only path forward is on a case-by-case basis. In determining feasibility of increasing GVWR/GAWRs, the OEM would need to provide an engineering review and documentation to support changing the original GVWR and/or GAWRs for a given chassis. Otherwise, the intermediate, final stage or altered stage manufacturer must determine compliance with all applicable regulatory requirements.

What about lowering GVWR?

There are a number of potential pitfalls for both the manufacturers and motor carriers regarding requests to derate GVWR on a new vehicle, and it cannot be assumed it’s possible to do. These situations involve careful consideration and OEM guidance before attempting to change OEM ratings.
Lowering GVWR could place the vehicle in a range where more regulatory compliance requirements apply (for which the intermediate-, final- or altered-stage manufacturer would become completely responsible).
Rerating to 10,000 pounds GVWR or below requires proof the vehicle meets multiple Canadian/Federal Motor Vehicle Safety Standard (C/FMVSS) crash test requirements, destructive tests and dynamic tests — all of which the company changing GVWR will be responsible to prove the modified vehicle meets.

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Disclaimer: This webpage and any related resources are intended for informational purposes only, and should not be used as a substitute for independent engineering analysis or judgment. This webpage and any related resources are not, and are not intended to, constitute legal advice or confirm legal compliance. To determine compliance with laws and engineering standards, consult with your own legal counsel and engineering experts.