ID Code § 49-1001 (2021)
2021 Idaho Code|Title 49 - MOTOR VEHICLES|Chapter 10 - WEIGHT, SPEED AND TIRE REGULATIONS|Section 49-1001 - ALLOWABLE GROSS LOADS.

49-1001. ALLOWABLE GROSS LOADS. The gross load imposed on the highway by any vehicle or combination of vehicles shall not exceed the limits in this section. The maximum single axle gross weight shall be twenty thousand (20,000) pounds, the maximum single wheel gross weight shall be ten thousand (10,000) pounds and the maximum gross vehicle or combination weight shall be one hundred five thousand five hundred (105,500) pounds, provided that maximum gross vehicle or combination weight on United States federal interstate and defense highways of this state shall not exceed eighty thousand (80,000) pounds, except as permitted under the provisions of section 49-1004, Idaho Code. (1) The total gross weight imposed on the highway by any group of consecutive axles shall be determined by the following formula:  W=500((LN/N-1)+12N+36)  Where W is the maximum weight in pounds (to the nearest 500 pounds) carried on any group of two (2) or more consecutive axles. L is the distance in feet between the extremes of any group of two (2) or more consecutive axles, and N is the number of axles under consideration. The formula is modified as illustrated in the following table:      Distance in feet between the extremes of any group of 2 or more consecutive   Maximum load in pounds carried on any group of 2 or more consecutive axles             axles   2 axles   3 axles   4 axles   5 axles   6 axles   7 axles   8 axles   9 axles   10 axles    11 axles   12 axles    13 axles     4   34,000                           5   34,000       WHEN NO ALLOWABLE WEIGHT IS               6   34,000       LISTED FOR ANY AXLE SPACING,               7   34,000       APPLY THE ALLOWABLE WEIGHT               8   34,000       AS LISTED IN THE FIRST COLUMN               8+   38,000   42,000     TO THE LEFT               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   82,000               29     57,500   61,500   66,000   71,500   77,000   82,500               30     58,500   62,000   66,500   72,000   77,500   83,000               31     59,000   62,500   67,500   72,500   78,000   83,500               32     60,000   63,500   68,000   73,000   78,500   84,500   90,000             33       64,000   68,500   74,000   79,000   85,000   90,500             34       64,500   69,000   74,500   80,000   85,500   91,000             35       65,500   70,000   75,000   80,500   86,000   91,500             36       66,000   70,500   75,500   81,000   86,500   92,000   98,000           37       66,500   71,000   76,000   81,500   87,000   93,000   98,500           38       67,500   71,500   77,000   82,000   87,500   93,500   99,000           39       68,000   72,500   77,500   82,500   88,500   94,000   99,500           40       68,500   73,000   78,000   83,500   89,000   94,500   100,000   106,000         41       69,500   73,500   78,500   84,000   89,500   95,000   100,500   106,500         42       70,000   74,000   79,000   84,500   90,000   95,500   101,000   107,000         43       70,500   75,000   80,000   85,000   90,500   96,000   102,000   107,500         44       71,500   75,500   80,500   85,500   91,000   96,500   102,500   108,000   114,000       45       72,000   76,000   81,000   86,000   91,500   97,500   103,000   108,500   114,500       46       72,500   76,500   81,500   87,000   92,500   98,000   103,500   109,000   115,000       47       73,500   77,500   82,000   87,500   93,000   98,500   104,000   110,000   115,500       48       74,000   78,000   83,000   88,000   93,500   99,000   104,500   110,500   116,000   122,000     49       74,500   78,500   83,500   88,500   94,000   99,500   105,000   111,000   116,500   122,500     50       75,500   79,000   84,000   89,000   94,500   100,000   105,500   111,500   117,000   123,000     51       76,000   80,000   84,500   89,500   95,000   100,500   106,000   112,000   118,000   123,500     52       76,500   80,500   85,000   90,500   95,500   101,000   107,000   112,500   118,500   124,000     53       77,500   81,000   86,000   91,000   96,500   102,000   107,500   113,000   119,000   124,500     54       78,000   81,500   86,500   91,500   97,000   102,500   108,000   113,500   119,500   125,000     55       78,500   82,500   87,000   92,000   97,500   103,000   108,500   114,000   120,000   125,500     56       79,500   83,000   87,500   92,500   98,000   103,500   109,000   115,000   120,500   126,000     57       80,000   83,500   88,000   93,000   98,500   104,000   109,500   115,500   121,000   127,000     58         84,000   89,000   94,000   99,000   104,500   110,000   116,000   121,500   127,500     59         85,000   89,500   94,500   99,500   105,000   110,500   116,500   122,000   128,000     60         85,500   90,000   95,000   100,500   105,500   111,000   117,000   122,500   128,500     61         86,000   90,500   95,500   101,000   106,000   112,000   117,500   123,000   129,000     62         87,000   91,000   96,000   101,500   107,000   112,500   118,000   124,000       63         87,500   92,000   96,500   102,000   107,500   113,000   118,500   124,500       64         88,000   92,500   97,500   102,500   108,000   113,500   119,000   125,000       65         88,500   93,000   98,000   103,000   108,500   114,000   119,500   125,500       66         89,500   93,500   98,500   103,500   109,000   114,500   120,000   126,000       67         90,000   94,000   99,000   104,500   109,500   115,000   121,000   126,500       68         90,500   95,000   99,500   105,000   110,000   115,500   121,500   127,000       69         91,000   95,500   100,000   105,500   111,000   116,000   122,000   127,500       70         92,000   96,000   101,000   106,000   111,500   117,000   122,500   128,000       71         92,500   96,500   101,500   106,500   112,000   117,500   123,000   128,500       72         93,000   97,000   102,000   107,000   112,500   118,000   123,500   129,000       73         93,500   98,000   102,500   107,500   113,000   118,500   124,000         74         94,500   98,500   103,000   108,000   113,500   119,000   124,500         75         95,000   99,000   103,500   109,000   114,000   119,500   125,000         76         95,500   99,500   104,500   109,500   114,500   120,000   126,000         77         96,000   100,000   105,000   110,000   115,000   120,500   126,500         78         97,000   101,000   105,500   110,500   116,000   121,000   127,000         79         97,500   101,500   106,000   111,000   116,500   122,000   127,500         80         98,000   102,000   106,500   111,500   117,000   122,500   128,000         81         98,500   102,500   107,000   112,000   117,500   123,000   128,500         82         99,000   103,000   108,000   113,000   118,000   123,500   129,000         83         100,000   104,000   108,500   113,500   118,500   124,000           84           104,500   109,000   114,000   119,000   124,500           85           105,000   109,500   114,500   120,000   125,000           86           105,500   110,000   115,000   120,500   125,500           87           106,000   111,000   115,500   121,000   126,000           88           107,000   111,500   116,000   121,500   127,000           89           107,500   112,000   117,000   122,000   127,500           90           108,000   112,500   117,500   122,500   128,000           91           108,500   113,000   118,000   123,000   128,500           92           109,000   113,500   118,500   123,500   129,000           93           110,000   114,000   119,000   124,000             94           110,500   115,000   119,500   125,000             95           111,000   115,500   120,000   125,500             96           111,500   116,000   121,000   126,000             97           112,000   116,500   121,500   126,500             98           113,000   117,000   122,000   127,000             99           113,500   118,000   122,500   127,500             100           114,000   118,500   123,000   128,000             101           114,500   119,000   123,500   129,000              (a) A public highway agency may limit the application of the weights authorized in this section as to certain highways within its jurisdiction which it determines have limited structural capacity of pavements, bridges, or other appurtenances. In designating such highways, it may specify a minimum wheelbase for combinations to be operated thereon. It may also designate specific highways or portions on which operation of a combination of vehicles with seven (7) through thirteen (13) axles will be subject to specified lesser allowable gross weights.  (b) Notwithstanding the figures shown in the table in this subsection (1), two (2) consecutive sets of tandem axles may carry a gross load of thirty-four thousand (34,000) pounds each, providing the overall distance between the first and last axles of such consecutive sets of tandem axles is thirty-six (36) feet or more.  (c) Vehicles may operate with reducible loads at gross weights greater than one hundred five thousand five hundred (105,500) pounds but not exceeding one hundred twenty-nine thousand (129,000) pounds on noninterstate highways in accordance with the provisions of section 49-1004, Idaho Code, provided such vehicles are in compliance with the weight formula specified in this subsection (1) of this section, have registered and have paid the registration fees as specified in section 49-434, Idaho Code, and are in compliance with the length restrictions set forth in section 49-1010(7), Idaho Code. (2) The weight limitations set forth in the table in subsection (1) of this section shall not apply to any vehicle, or combination of vehicles when a greater allowed weight in pounds would be permitted such vehicles under the table provided in this subsection, except that with regard to transportation on the United States federal interstate and defense highways of this state, the following table of allowable weights shall apply only to vehicles engaged in the transportation of logs, pulp wood, stull, rough lumber, poles or piling; or to any such vehicle engaged in the transportation of ores, concentrates, sand and gravel and aggregates thereof, in bulk; or to any such vehicle engaged in the transportation of agricultural commodities, including livestock:      Distance in feet between   Allowed Load in Pounds     the extremes of any group   Vehicles with   Vehicles with     of 2 or more consecutive   Three or Four   Five or more     axles   axles   axles      3 through 12   37,800   37,800     13   56,470   56,470     14   57,940   57,940     15   59,400   59,400     16   60,610   60,610     17   61,820   61,820     18   63,140   63,140     19   64,350   64,350     20   65,450   65,450     21   66,000   66,330     22   66,000   67,250     23   66,000   67,880     24   66,000   68,510     25   66,000   69,150     26   66,000   69,770     27   66,000   70,400     28   66,000   70,950     29   66,000   71,500     30   66,000   72,050     31     72,600     32     73,150     33     73,700     34     74,250     35     74,800     36     75,350     37     75,900     38     76,450     39     77,000     40     77,550     41     78,100     42     78,650      43 and over     79,000      The weight allowances provided in this subsection do not apply if the total gross weight of a vehicle or combination of vehicles is intended to exceed seventy-nine thousand (79,000) pounds as declared by the operator. When the provisions of this subsection are applicable to a vehicle or combination of vehicles, it shall be a violation of the provisions of this subsection if that vehicle or combination of vehicles exceeds the weights specified in this table. (3) In determining the gross weight of a vehicle or the gross weight of any two (2) or more consecutive axles under subsection (1) or (2) or (9) of this section, the total gross weight of the vehicle or combination of vehicles or the gross weight of any two (2) or more consecutive axles shall be the sum of the axle weights. For the purposes of this chapter the gross weight of a vehicle or the gross weight of any two (2) or more consecutive axles may be determined by accumulatively adding the separate weights of individual axles and tandem axles or groups of axles to determine gross weight. The results of any weighing at a temporary or permanent port of entry and the records relating to the calibration and accuracy of any scale at a temporary or permanent port of entry shall be admissible in any proceeding in this state. In order to prove a violation of the provisions of this section the state must show that: (a) The sum of the axle weights exceeds what is allowable under the provisions of subsection (1) or (2) or (9) of this section;  (b) The scale involved in the weighing was at the time of weighing calibrated in conformity with and met the accuracy requirements of the standards for the enforcement of traffic and highway laws as set forth in the latest edition of handbook 44 of the national institute of standards and technology; (c) Weights of individual axles or axles within a commonly suspended group of axles supported by a mechanical system designed to distribute equal wheel loads to individual axles in the group were utilized only to determine gross weights of that group of axles, and that any further evaluation of gross weights of combinations of axles considered only the accumulated gross weight of each such commonly suspended group of axles. (4) In applying the weight limitations imposed in this section, a vehicle or combination of vehicles must comply exclusively with the weight limitations in either subsection (1) or (2) or (9) of this section. (5) In applying the weight limitations imposed in this section, the distance between axles shall be measured to the nearest even foot. When a fraction is exactly one-half (1/2) foot the next larger whole number shall be used. (6) The limitations imposed in this section are in addition and supplemental to all other laws imposing limitations upon the size and weight of vehicles. Further, single axles within groups of axles are subject to the provisions and limitations of this chapter. Single axles within groups of axles may be weighed and evaluated separately. (7) Notwithstanding the other provisions of this chapter, no vehicle, motor vehicle, trailer and/or semitrailer, or combination thereof, may be operated on the public highways of the state under loads which would result in the withholding of funds by operation of controlling federal law as provided in the Federal Aid Highway Act of 1956, as amended. (8) Except as provided herein, no vehicle or combination of vehicles may proceed past the place of weighing at temporary or permanent ports of entry or checking stations when: the weight of a single axle exceeds the maximum limitations set forth herein by two thousand (2,000) pounds or more; the weight of a combination of axles, or gross vehicle weight exceeds the maximum allowable weight as set forth herein by seven percent (7%) or more. Vehicles or combinations of vehicles which exceed the weight limitations set forth herein shall be required to be brought into compliance with applicable weight limitations contained within this subsection at the place of weighing prior to continuing, except those vehicles or combinations of vehicles which are transporting loads which, in the determination of the board or other proper authorities in charge of or having jurisdiction over a highway, are deemed unsafe or impractical to bring into compliance at the place of weighing, and except those vehicles which do not exceed fifteen percent (15%) over maximum axle and axle group weights set forth in this section. Vehicles or combinations of vehicles transporting loads in this latter category shall obtain a travel authorization to the nearest place of safe unloading, load adjustment or other means of legalization. (a) Neither the state of Idaho or its employees, nor any authority and its employees in charge of or having jurisdiction over a highway, shall be held liable for personal injury or property damage resulting from the requirements of section 49-1001(8), Idaho Code. (b) The fee for a travel authorization as set forth above shall be fifty dollars ($50.00) and shall be on a form prescribed by the board or other proper authorities, and shall not be construed as contributing to a reduction in the penalties prescribed in section 49-1013, Idaho Code. (c) The board or other proper authorities in charge of or having jurisdiction over a highway shall adopt and enforce administrative rules as may be necessary to carry out the provisions of this section. (9) For vehicles on all highways except the United States federal interstate and defense highways of this state, the following table shall apply:      Distance in feet between   Allowed Load in Pounds     the extremes of any group   Vehicles with   Vehicles with     of 2 or more consecutive   Three or Four   Five or more     axles   axles   axles      3 through 12   37,800   37,800     13   56,470   56,470     14   57,940   57,940     15   59,400   59,400     16   60,610   60,610     17   61,820   61,820     18   63,140   63,140     19   64,350   64,350     20   65,450   65,450     21   66,000   66,330     22   66,000   67,250     23   66,000   67,880     24   66,000   68,510     25   66,000   69,150     26   66,000   69,770     27   66,000   70,400     28   66,000   70,950     29   66,000   71,500     30   66,000   72,050     31     72,600     32     73,150     33     73,700     34     74,250     35     74,800     36     75,350     37     75,900     38     76,450     39     77,000     40     77,550     41     78,100     42     78,650      43 and over     80,000      The weight allowances provided in this subsection do not apply if the total gross weight of a vehicle or combination of vehicles is intended to exceed eighty thousand (80,000) pounds as declared by the operator. When the provisions of this subsection are applicable to a vehicle or combination of vehicles, it shall be a violation of the provisions of this subsection if that vehicle or combination of vehicles exceeds the weights specified in this table. (10) Variable load suspension axles shall meet the following criteria in order to be included in the computation of gross vehicle or axle weight limits for vehicles under the provisions of this section: (a) The deployment control switch for such axles may be located inside of the driver’s compartment but the pressure regulator valve for the operation of pressure on the pavement shall be located outside of and inaccessible to the driver’s compartment.  (b) The manufacturer’s gross axle weight rating of each such axle must not be less than the actual loading of the axle. (c) All variable load suspension axles shall be designed to be self-steering; provided however, variable load suspension axles that are within sixty (60) inches of a drive axle or are within sixty (60) inches of a trailer axle, need not be self-steering.  (d) The manufacturer’s gross tire weight rating of each tire must not be less than the actual loading of the tire. (e) Variable load suspension axles must be fully deployed or fully raised. For applicable definitions, see sections 49-117 and 49-123, Idaho Code. (11) Any person who operates a motor vehicle with a variable load suspension axle in violation of the provisions of this section shall be subject to the penalties provided in section 49-1013, Idaho Code.  History: [49-1001, added 1988, ch. 265, sec. 272, p. 715; am. 1991, ch. 226, sec. 1, p. 538; am. 1993, ch. 273, sec. 4, p. 921; am. 1993, ch. 334, sec. 3, p. 1238; am. 1993, ch. 345, sec. 1, p. 1284; am. 1993, ch. 371, sec. 1, p. 1334; am. 1993, ch. 376, sec. 2, p. 1380; am. 1994, ch. 321, sec. 4, p. 1030; am. 1995, ch. 72, sec. 1, p. 183; am. 1995, ch. 122, sec. 3, p. 532; am. 1998, ch. 158, sec. 2, p. 535; am. 1998, ch. 189, sec. 1, p. 684; am. 2000, ch. 418, sec. 15, p. 1352; am. 2007, ch. 65, sec. 1, p. 159; am. 2015, ch. 208, sec. 9, p. 648.]