2020 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.]
