In the U.S., federal regulations at 49 CFR 567.4(g)(3) require GVWR be calculated assuming:
- 150 lbs per passenger seat, and
- manufacturer's rated cargo load, and
- unloaded vehicle weight (curb weight)
49 CFR 567.4(h) provides for multiple GVWRs (and GVARs) for different tire sizes and/or reduced speeds.
49 CFR 567.4
(g) The label shall contain the following statements, in the English language, lettered in block capitals and numerals not less than three thirty-seconds of an inch high, in the order shown:
...
(3) “Gross Vehicle Weight Rating” or “GVWR” followed by the appropriate value in pounds, which shall not be less than the sum of the unloaded vehicle weight, rated cargo load, and 150 pounds times the number of the vehicle's designated seating positions. However, for school buses the minimum occupant weight allowance shall be 120 pounds per passenger and 150 pounds for the driver.
(h)
Multiple GVWR-GAWR ratings.
(1) (For passenger cars only) In cases in which different tire sizes are offered as a customer option, a manufacturer may at its option list more than one set of values for GVWR and GAWR, to meet the requirements of
paragraphs (g) (3) and
(4) of this section. If the label shows more than one set of weight rating values, each value shall be followed by the phrase “with __tires,” inserting the proper tire size designations. A manufacturer may, at its option, list one or more tire sizes where only one set of weight ratings is provided.
(2) (For multipurpose passenger vehicles, trucks, buses, trailers, and motorcycles) The manufacturer may, at its option, list more than one GVWR-GAWR-tire-rim combination on the label, as long as the listing contains the tire-rim combination installed as original equipment on the vehicle by the manufacturer and conforms in content and format to the requirements for tire-rim-inflation information set forth in Standard Nos. 110, 120, 129 and 139 (
§§ 571.110,
571.120,
571.129 and
571.139 of this chapter).
(3) At the option of the manufacturer, additional GVWR-GAWR ratings for operation of the vehicle at reduced speeds may be listed at the bottom of the certification label following any information that is required to be listed.