Section 266:18-a - Weight on Non-Interstate and General Highway System The driving on ways of this state, other than on the interstate and defense highway system as provided by RSA 266:18, of any vehicle or combination of vehicles 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.
I. Maximum tire and axle gross weights allowable:(a) The manufacturer's load rating for the tires.(b) Two axles less than 40 inches apart shall be considered as a single axle unit.(c) When being driven on any way other than the interstate and defense highway system with a gross weight not in excess of 73,280 pounds:(1) 22,400 pounds per axle on 3-axle single unit vehicles and on all other vehicles with axles 10 feet or more apart, including combination vehicles;(2) 18,000 pounds per axle on axles of vehicles less than 10 feet apart, except 3-axle single unit vehicles.II. Maximum allowable vehicle gross weight:(a) For 2-axle vehicles, 33,400 pounds.(b) For single unit 3-axle vehicles, 55,000 pounds, or a gross weight not in excess of that produced by application of the weight formula as defined in subparagraph (h), whichever is greater, as shown in table III in subparagraph (h).(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) 60,000 pounds, or a gross weight not in excess of that produced by application of the weight formula as defined in subparagraph (h), whichever is the greater; or(2) If a heavy duty recovery vehicle, 80,000 pounds, or a gross weight not in excess of that produced by application of the weight formula as defined in subparagraph (h), whichever is the greater.(d) For a single unit 5-axle heavy duty recovery vehicle, 84,000 pounds, or a gross weight not in excess of that produced by application of the weight formula as defined in subparagraph (h), whichever is the greater. 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 Extreme Axles in Feet | Maximum Gross Weight 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 group of 2 or more consecutive axles shall not exceed that produced by application of the weight formula as defined in subparagraph (h).
(f) For a combination of truck-tractor and semi-trailer equipped with 4 axles, the gross weight shall not exceed that set forth in table II as follows: Table II.
Distance Between Extreme Axles in Feet | Maximum Gross Weight in Pounds |
28 | 60,500 |
29 | 61,500 |
30 | 62,000 |
31 | 62,500 |
32 | 63,500 |
33 | 64,000 |
34 | 64,500 |
35 | 65,500 |
36 | 66,000 |
37 | 66,500 |
38 | 67,500 |
39 | 68,000 |
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 group of 2 or more consecutive axles shall not exceed that produced by application of the weight formula as defined in subparagraph (h).
(g) For a combination of truck-tractor and single semi-trailer with 5 or more axles with gross weight not in excess of 73,280 pounds, 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.(h) For a combination of truck-tractor and single semi-trailer equipped with 5 or more axles with a gross weight in excess of 73,280 pounds or a combination of truck-tractor and more than one trailing unit, the total gross weight shall not exceed 80,000 pounds including all law enforcement tolerances, and the overall gross weight on a group of 2 or more consecutive axles shall not exceed that produced by application of the following formula, known as the weight formula. Click here to view image
(In which W equals overall gross weight on any group of 2 or more consecutive axles to the nearest 500 pounds; L equals the distance measured to the nearest foot between the extreme of any group of 2 or more consecutive axles; and N equals the number of axles in the group under consideration.) Except that 2 consecutive sets of tandem axles may carry a gross load of 34,000 pounds each, provided the overall distance between the first and last axles of such consecutive sets of tandem axles is 36 feet or more and provided that such gross weight shall not exceed 80,000 pounds, including all law enforcement tolerances.
Click here to view image
when expressed in tabular form results in maximum allowable load in pounds carried on any group of 2 or more consecutive axles as follows in table III.
Table III.
Distance* | 2 axles | 3 axles | 4 axles | 5 axles | 6 axles | 7 axles |
4 | 34,000 |
5 | 34,000 |
6 | 34,000 |
7 | 34,000 |
8 and less | 34,000 | 34,000 |
more than 8 | 38,000 | 42,000 |
9 | 39,000 | 42,500 |
10 | 40,000 | 43,500 |
11 | 44,000 |
12 | 45,000 | 50,000 |
13 | 45,500 | 50,500 |
14 | 46,500 | 51,500 |
15 | 47,000 | 52,000 |
16 | 48,000 | 52,500 | 58,000 |
17 | 48,500 | 53,500 | 58,500 |
18 | 49,500 | 54,000 | 59,000 |
19 | 50,000 | 54,500 | 60,000 |
20 | 51,000 | 55,500 | 60,500 | 66,000 |
21 | 51,500 | 56,000 | 61,000 | 66,500 |
22 | 52,500 | 56,500 | 61,500 | 67,000 |
23 | 53,000 | 57,500 | 62,500 | 68,000 |
24 | 54,000 | 58,000 | 63,000 | 68,500 | 74,000 |
25 | 54,500 | 58,500 | 63,500 | 69,000 | 74,500 |
26 | 55,500 | 59,500 | 64,000 | 69,500 | 75,000 |
27 | 56,000 | 60,000 | 65,000 | 70,000 | 75,500 |
28 | 57,000 | 60,500 | 65,500 | 71,000 | 76,500 |
29 | 57,500 | 61,500 | 66,000 | 71,500 | 77,000 |
30 | 58,500 | 62,000 | 66,500 | 72,000 | 77,500 |
31 | 59,000 | 62,500 | 67,500 | 72,500 | 78,000 |
32 | 60,000 | 63,500 | 68,000 | 73,000 | 78,500 |
33 | 64,000 | 68,500 | 74,000 | 79,000 |
34 | 64,500 | 69,000 | 74,500 | 80,000 |
35 | 65,500 | 70,000 | 75,000 |
**36 | 66,000 | 70,500 | 75,500 |
**37 | 66,500 | 71,000 | 76,000 |
**38 | 67,500 | 71,500 | 77,000 |
39 | 68,000 | 72,500 | 77,500 |
40 | 68,500 | 73,000 | 78,000 |
41 | 69,500 | 73,500 | 78,500 |
42 | 70,000 | 74,000 | 79,000 |
43 | 70,500 | 75,000 | 80,000 |
44 | 71,500 | 75,500 |
45 | 72,000 | 76,000 |
46 | 72,500 | 76,500 |
47 | 73,500 | 77,500 |
48 | 74,000 | 78,000 |
49 | 74,500 | 78,500 |
50 | 75,500 | 79,000 |
51 | 76,000 | 80,000 |
52 | 76,500 |
53 | 77,500 |
54 | 78,000 |
55 | 78,500 |
56 | 79,500 |
57 | 80,000 |
* Distance in feet between the extremes of any group of 2 or more consecutive axles.
**Distance in feet between the extremes of 4 axles. (2 sets of 2 axles) 68,000 gross weight exception.
The permissible loads are computed to the nearest 500 pounds.
(i) The following loaded vehicles shall not be driven over H15-44 bridges: (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 1-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 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 80,000 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 subparagraph (h) and shall be limited to a total combined gross weight not in excess of 80,000 pounds, a single axle limit of 20,000 pounds and a tandem axle limit of 34,000 pounds.Amended by 2018 , 74: 3, eff. 7/24/2018.1983, 434:16. 1986, 121:3; 136:7. 1987, 404:21. 2008, 39 : 1 , eff. July 11, 2008. 2018, 74 : 3 , eff. July 24, 2018.