Section 1391 - Tire and axle limits(a) Except as otherwise provided in this chapter, a person or corporation shall not operate or cause to be operated a tractor, trailer, semi-trailer, motor truck, or any other motor vehicle without sufficient weight maintained upon the front axle of such vehicle to make such vehicle safe in operation, nor shall the maximum load on any axle of such vehicle exceed a gross weight of more than 600 pounds per inch of tire width computed in conformity with the manufacturer's designated width.(b) No single axle load shall be in excess of 22,400 pounds and a 10 percent tolerance shall be allowed on each single axle load, nor shall any tandem axle load be in excess of 36,000 pounds, with a 10 percent tolerance allowed, except in the case of such vehicles owned by persons to whom special permits shall be issued in accordance with the provisions of section 1400 of this title.(c) Unless federal law authorizes the axle load limits, tolerances, or both, provided for in subsection (b) of this section to apply on those highways designated as the Dwight D. Eisenhower National System of Interstate and Defense Highways, no single axle load on those highways shall be in excess of 20,000 pounds with no tolerance allowed, nor shall any tandem axle load be in excess of 34,000 pounds, with no tolerance allowed, except in the case of vehicles owned by persons to whom special permits have been issued in accordance with section 1400 of this title.Amended by 2021 , No. 20, § 245, eff. 7/1/2021.Amended 1963, No. 206, § 4; 1964, No. 4 (Sp. Sess.), eff. 2/27/1964; 1971, No. 226 (Adj. Sess.), § 6; 1977, No. 41, § 1, eff. 4/19/1977; 1983, No. 86, § 1; 1991, No. 72, § 4; 2009 , No. 63 (Adj. Sess.) , § 1, eff. 1/13/2010; 2009 , No. 63 (Adj. Sess.) , § 3, see effective date note; 2011 , No. 23 , § 1, eff. 5/11/2011.