49 CFR 179.13
Tank car capacity and gross weight limitation.
(a) Except as provided in paragraph (b) of this section, tank cars built after November 30, 1970, may not exceed 34,500 gallons (130,597 L) capacity or 263,000 pounds gross weight on rail. Existing tank cars may not be converted to exceed 34,500 gallons capacity or 263,000 pounds gross weight on rail.
(b) Tank cars meeting the applicable authorized tank car specifications listed in § 173.244(a)(2) or (3), or § 173.314(c) or (d) may not exceed 34,500 gallons (130,597 L) capacity or 286,000 pounds (129,727 kg) gross weight on rail. Tank cars exceeding 263,000 pounds and up to 286,000 pounds gross weight on rail must meet the requirements of AAR Standard S-286, Free/Unrestricted Interchange for 286,000 Lb Gross Rail Load Cars (IBR; see § 171.7 of this subchapter), except that any increase in weight above 263,000 may not be used to increase commodity quantity.
[74 FR 1802, Jan. 13, 2009]