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)

Terms Used In Idaho Code 49-1001

  • Jurisdiction: (1) The legal authority of a court to hear and decide a case. Concurrent jurisdiction exists when two courts have simultaneous responsibility for the same case. (2) The geographic area over which the court has authority to decide cases.
  • person: includes a corporation as well as a natural person;
Idaho Code 73-114
  • Property: includes both real and personal property. See Idaho Code 73-114
  • State: when applied to the different parts of the United States, includes the District of Columbia and the territories; and the words "United States" may include the District of Columbia and territories. See Idaho Code 73-114
    • 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.