2020 Idaho Code
Title 49 - MOTOR VEHICLES
Chapter 10 - WEIGHT, SPEED AND TIRE REGULATIONS
Section 49-1001 - ALLOWABLE GROSS LOADS.

Universal Citation: ID Code § 49-1001 (2020)

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.]

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