49 CFR § 392.51 - Reserve fuel; materials of trade.
Small amounts of fuel for the operation or maintenance of a commercial motor vehicle (including its auxiliary equipment) may be designated as materials of trade (see 49 CFR 171.8).
(a) The aggregate gross weight of all materials of trade on a motor vehicle may not exceed 200 kg (440 pounds).
(b) Packaging for gasoline must be made of metal or plastic and conform to requirements of 49 CFR Parts 171, 172, 173, and 178 or requirements of the Occupational Safety and Health Administration contained in 29 CFR 1910.106.
(c) For Packing Group II (including gasoline), Packing Group III (including aviation fuel and fuel oil), or ORM-D, the material is limited to 30 kg (66 pounds) or 30 L (8 gallons).
(d) For diesel fuel, the capacity of the package is limited to 450 L (119 gallons).
(e) A Division 2.1 material in a cylinder is limited to a gross weight of 100 kg (220 pounds). (A Division 2.1 material is a flammable gas, including liquefied petroleum gas, butane, propane, liquefied natural gas, and methane).