2014 New Hampshire Revised Statutes
Title XXI - MOTOR VEHICLES
Chapter 266 - EQUIPMENT OF VEHICLES
Section 266:18-b - Weight on Non-Interstate and General Highway System for Vehicles With Additional Registration.

    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, 73,000 pounds. 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.
       (d) 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:

 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.
       (e) 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 %45*%46 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.
       (f) 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.
       (g) 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.
       (h) The commissioner of transportation may restrict at his discretion the crossing of certain bridges or other structures, which he 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.
       (i) 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.
       (j) 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(e) 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.

Source. 1986, 121:3. 1987, 404:22, eff. July 25, 1987.