TITLE XXI
MOTOR VEHICLES

CHAPTER 266
EQUIPMENT OF VEHICLES

Weight

Section 266:18-b

    266:18-b Weight on Non-Interstate and General Highway System for Vehicles With Additional Registration. –
The provisions of this section shall only apply to vehicles or combinations of vehicles which have been certified pursuant to RSA 266:18-d and shall only apply to the driving of such vehicles on any way other than the interstate and defense highway system. The driving of any such vehicle exceeding the limitations of this section is hereby prohibited; provided, however, that any police officer shall allow on any way other than the interstate and defense highway system a tolerance of 5 percent above said limitations and 10 percent above said limitations on the axle weights.
I. The maximum gross weights allowable for tires shall be the manufacturer's load rating for the tire.
II. Maximum axle weights allowable:
(a) 22,400 pounds per axle on 3-axle single unit vehicles and 20,000 pounds per axle on 4-axle single unit vehicles and 22,400 pounds on all other vehicles with axles 10 feet or more apart, including combination vehicles.
(b) 18,000 pounds per axle on axles of vehicles less than 10 feet apart, except 3-axle single unit vehicles and 4-axle single unit vehicles.
(c) Two axles less than 40 inches apart shall be considered as a single axle unit.
(d) The distribution of loads shall be further controlled as:
(1) No single axle of a tandem unit shall support more than 60 percent of the total weight supported by the tandem unit. It shall not be considered a violation if neither axle of a tandem unit exceeds the weight legally allowed on a single axle unit for the same vehicle.
(2) No single axle of a tri-axle unit shall support more than 40 percent of the total weight supported by the tri-axle unit.
(3) The allowable gross weight of a vehicle shall not be increased by the addition of a trailing axle, so called, unless the trailing axle supports at least 50 percent of the added weight permitted by the addition of that trailing axle.
III. Maximum allowable vehicle gross weights:
(a) For 2-axle vehicles, 37,400 pounds.
(b) For single unit 3-axle vehicles, 65,000 pounds.
(c) For single unit 4-axle vehicles, provided that such vehicles shall have drive on 2 rear axles, and the tridem may contain not more than one retractable axle and, if not factory installed and load equalizing, must provide a system of load equalization by hydraulic, pneumatic, or mechanical means, and be equipped with brakes:
(1) 73,000 pounds; or
(2) If a heavy duty recovery vehicle, 84,000 pounds.
(d) For a single unit 5-axle heavy duty recovery vehicle, 99,000 pounds, provided that such vehicles shall have drive on 2 rear axles, and the tridem may contain not more than one retractable axle and, if not factory installed and load equalizing, must provide a system of load equalization by hydraulic, pneumatic, or mechanical means, and be equipped with brakes.
(e) For a combination of truck-tractor and semi-trailer equipped with 3 axles, the gross weight shall not exceed that set forth in table I as follows:
Table I.
Distance Between Maximum Gross Weight
Extreme Axles in Feet in Pounds
25 54,500
26 55,500
27 56,000
28 57,000
29 57,500
30 58,500
31 59,000
32 60,000
Further provided that the maximum tire and axle gross weights as provided in paragraph I shall apply, and the maximum load in pounds carried on any axle shall not exceed that provided in paragraph II.
(f) For a combination of truck-tractor and semi-trailer equipped with 4 axles or more, the gross weight shall not exceed that set forth in the following table:
Distance* Total Axles Gross Wt.
8 4 or more 59,000
9 60,000
10 61,000
11 62,000
12 63,000
13 64,000
14 65,000
15 66,000
16 67,000
17 68,000
18 69,000
19 5 or more 70,000
20 72,000
21 74,000
22 76,000
23 78,000
24 80,000
25 80,000
26 80,000
27 80,000
28 82,000
29 84,000
30 6 or more 86,000
31 88,000
32 90,000
33 92,500
34 95,000
35 97,500
36 99,000
* The distance in feet noted is that between extreme axles, excluding the steering axle.
Further provided that the maximum tire and axle gross weights as provided in paragraphs I and II shall apply.
(g) For a combination of truck-tractor and single semi-trailer with 4 or more axles, the weight on any single axle shall not exceed 22,400 pounds and the weight on any tandem axle shall not exceed 36,000 pounds, and the weight of any tri-axle shall not exceed 54,000 pounds. For a combination of truck-tractor and single semi-trailer with 4 or more axles that is carrying raw forestry products, the weight on any tandem axle shall not exceed 40,000 pounds. For purposes of this subparagraph, "raw forestry products" means unprocessed logs and wood chips harvested from forestland, as defined in RSA 227-G:2, VIII, that have not previously been moved off site.
(h) For a combination of truck-tractor and one or more trailing units being driven upon any way of this state, the total gross weight shall not exceed 99,000 pounds.
(i) The commissioner of transportation may restrict at his or her discretion the crossing of certain bridges or other structures, which he or she determines to have insufficient strength to safely carry multiple legal loads, by limiting vehicles to a caution crossing, whereby the bridge is restricted to one vehicle certified under RSA 266:18-d exceeding 37,400 pounds on the bridge at any one time. When multiple vehicles of more than 2 axles are located on the designated bridge, all loaded certified vehicles shall be required to stop and wait until other traffic passes before crossing the bridge. A bridge so restricted shall be posted according to RSA 266:18-c.
(j) The following loaded vehicles shall not be driven over H15-44 bridges unless so authorized by the commissioner of transportation:
(1) A combination vehicle equipped with 5 axles in the configuration of 3-axle truck-tractor and 2-axle semi-trailer with wheel base less than 38 feet or 2-axle truck-tractor with one-axle semi-trailer and 2-axle full trailer with wheel base less than 45 feet.
(2) A loaded single unit vehicle with full trailer equipped with 6 axles with wheel base less than 45 feet.
(3) Vehicles with 7, 8, or 9 axles.
(k) Coupled vehicles consisting of a truck together with a trailer attached to the truck by a pintle hook or similar coupling device with adequate breakaway protection as provided in RSA 266:63 may be driven, provided the total combined gross weight of the vehicles does not exceed 99,000 pounds and provided that each unit of the coupled vehicles shall be limited to the maximum permissible axle weights and gross weights of the individual units, and further provided that the weight of 2 or more consecutive axles of the coupled vehicle shall not be in excess of that produced by application of the weight formula as defined in RSA 266:18-b, III(f) and shall be limited to a total combined gross weight not in excess of 99,000 pounds, a single axle limit of 22,400 pounds, a tandem axle limit of 36,000 pounds, and a tri-axle limit of 54,000 pounds.
(l) For a combination of truck-tractor and dump trailer equipped with 6 axles or more, the gross weight shall not exceed 99,000 pounds if the distance between the extreme axles, excluding the steering axle, is 28 feet or more. If the distance between the extreme axles is less than 28 feet, the maximum weight shall be determined under subparagraph (f).

Source. 1986, 121:3. 1987, 404:22, eff. July 25, 1987. 2016, 193:1, eff. June 30, 2016. 2018, 74:4, eff. July 24, 2018. 2021, 204:2, Pt. VII, Sec. 1, eff. Oct. 9, 2021.