§ 39-12-05 — Weight limitations for vehicles on interstate system

A person may not operate on a highway which is part of the interstate system any vehicle:
1. With a single axle that carries a gross weight in excess of twenty thousand pounds
[9071.85 kilograms] or a wheel load over ten thousand pounds [4535.92 kilograms]. A
wheel may not carry a gross weight over five hundred fifty pounds [249.48 kilograms]
for each inch [2.54 centimeters] of tire width except that such limits may not be applied
to tires on the steering axle. Steering axle weights are limited to twenty thousand
pounds [9071.85 kilograms] or the axle rating established by the manufacturer,
whichever is lower. Axles spaced forty inches [101.60 centimeters] apart or less are
considered as one axle and, on axles spaced over forty inches [101.60 centimeters]
and under eight feet [2.44 meters] apart, the axle load may not exceed seventeen
thousand pounds [7711.07 kilograms] per axle. The wheel load, in any instance, may
not exceed one-half the allowable axle load. Spacing between axles is measured from
axle center to axle center.
2. Subject to the limitations imposed by subsection 1 on tires, wheel, and axle loads, the
gross weight of which exceeds that determined by the formula of:
W = 500 (LN/ + 12N + 36)
N-1
where W equals maximum weight in pounds carried on any group of more than one
axle; L equals distance in feet between the extremes of any group of consecutive
axles; and N equals number of axles in the group under consideration, except that two
consecutive sets of tandem axles may carry a gross load of thirty-four thousand
pounds [15422.14 kilograms] each, providing the overall distance between the first and
last axles of the consecutive sets of tandem axles is at least thirty-six feet [10.97
meters]. The gross weight may not exceed eighty thousand pounds [36287.39
kilograms].