Iowa Code
Chapter 321 - MOTOR VEHICLES AND LAW OF THE ROAD
Section 321.463 - Maximum gross weight — exceptions — penalties.

321.463 Maximum gross weight — exceptions — penalties.
1. An axle may be divided into two or more parts, except that all parts in the same vertical transverse plane shall be considered as one axle.
2. The gross weight on any one axle of a vehicle, or of a combination of vehicles, operated on the highways of this state, shall not exceed twenty thousand pounds on an axle equipped with pneumatic tires, and shall not exceed fourteen thousand pounds on an axle equipped with solid rubber tires. The gross weight on any tandem axle of a vehicle, or any combination of vehicles, shall not exceed thirty-four thousand pounds on an axle equipped with pneumatic tires. This subsection does not apply to implements of husbandry.
3. Notwithstanding other provisions of this chapter to the contrary, indivisible loads operating under the permit requirements of sections 321E.7, 321E.8, 321E.9, 321E.29A, and 321E.29B, and divisible loads operating under the permit requirements of section 321E.26, shall be allowed a maximum of twenty thousand pounds per axle.
4. a. (1) Notwithstanding any provision of this section to the contrary, the weight on any one axle of a self-propelled implement of husbandry used exclusively for the application of organic or inorganic plant food materials, agricultural limestone, or agricultural chemicals operated on the highways of this state shall not exceed twenty-five thousand pounds.
(2) A self-propelled implement of husbandry used exclusively for the application of organic or inorganic plant food materials, agricultural limestone, or agricultural chemicals shall comply with the other provisions of this section and chapter when operated over a bridge in this state, other than any provision limiting the weight on any one axle to less than twenty-five thousand pounds. A local authority may issue a special permit, based on a statewide standard developed by the department, allowing the operation over a bridge within its jurisdiction of such a self-propelled implement of husbandry with a weight in excess of the weights allowed under this chapter.
b. (1) Notwithstanding any provision of this section to the contrary, the weight on any one axle of a fence-line feeder, grain cart, or tank wagon operated on the highways of this state shall not exceed twenty-four thousand pounds from February 1 through May 31 or twenty-eight thousand pounds from June 1 through January 31, provided, however, that the maximum gross vehicle weight of the fence-line feeder, grain cart, or tank wagon shall not exceed ninety-six thousand pounds.
(2) Notwithstanding any provision of this section to the contrary, a tracked implement of husbandry operated on the highways of this state shall not have a maximum gross weight in excess of ninety-six thousand pounds.
(3) A fence-line feeder, grain cart, tank wagon, or tracked implement of husbandry shall comply with the other provisions of this section and chapter when operated over a bridge in this state. A local authority may issue a special permit, based on a statewide standard developed by the department, allowing the operation over a bridge within its jurisdiction of a fence-line feeder, grain cart, tank wagon, or tracked implement of husbandry with a weight in excess of the weights allowed under this chapter.
(4) For purposes of this paragraph “b”:
(a) “Highway” does not include a bridge.
(b) “Fence-line feeder, grain cart, or tank wagon” means any fence-line feeder, grain cart, or tank wagon.
5. a. Notwithstanding any provision of law to the contrary, a motor vehicle equipped with an engine fueled primarily by natural gas may exceed any applicable maximum gross weight limit under this chapter, up to a maximum gross weight of eighty-two thousand pounds, by an amount equal to the difference between the weight of the vehicle attributable to the natural gas tank and fueling system installed in the vehicle and the weight of a comparable diesel fuel tank and fueling system.
b. Notwithstanding any provision of law to the contrary, a motor vehicle described in paragraph “a” equipped with an auxiliary power or idle reduction technology unit that reduces fuel use and emissions during engine idling may exceed any applicable maximum gross weight limit under this chapter by five hundred fifty pounds or the weight of the auxiliary power or idle reduction technology unit, whichever is less. This paragraph “b” shall not apply unless the operator of the vehicle provides to the department a written certification of the weight of the auxiliary power or idle reduction technology unit, demonstrates or certifies to the department that the idle reduction technology unit is fully functional at all times, and carries with the operator the written certification of the weight of the auxiliary power or idle reduction technology unit in the vehicle at all times to present to law enforcement in the event the vehicle is suspected of violating any applicable weight restrictions.
6. a. The maximum gross weight allowed to be carried on a vehicle or combination of vehicles on highways which are part of the primary road system is as follows:
MAXIMUM GROSS WEIGHT TABLE — PRIMARY HIGHWAYS
Distance
in feet 2 Axles 3 Axles 4 Axles 5 Axles 6 Axles7 Axles
4 34,000
5 34,000
6 34,000
7 34,000 34,000
8 34,000 34,000
8’1” 38,000 42,000
9 39,000 42,500
10 40,000 43,500 48,500
11 44,000 49,500
12 45,000 50,000
13 45,500 50,500 56,000
14 46,500 51,500 57,000
15 47,000 52,000 57,500
16 48,000 52,500 58,000
17 48,500 53,500 58,500 64,000
18 49,500 54,000 59,000 65,000
19 50,000 54,500 60,000 65,500
20 51,000 55,500 60,500 66,00071,500
21 51,500 56,000 61,000 66,50072,500
22 52,500 56,500 61,500 67,00073,000
23 53,000 57,500 62,500 68,00073,500
24 54,000 58,000 63,000 68,50074,000
25 54,500 58,500 63,500 69,00074,500
26 55,500 59,500 64,000 69,50075,000
27 56,000 60,000 65,000 70,00076,000
28 57,000 60,500 65,500 71,00076,500
29 57,500 61,500 66,000 71,50077,000
30 58,500 62,000 66,500 72,00077,500
31 59,000 62,500 67,500 72,50078,000
32 60,000 63,500 68,000 73,00078,500
33 64,000 68,500 74,00079,500
34 64,500 69,500 74,50080,000
35 65,500 70,000 75,000
36 68,000 70,500 75,500
37 68,000 71,000 76,000
38 68,000 72,000 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
b. The maximum gross weight allowed to be carried on a vehicle or combination of vehicles on nonprimary highways is as follows:
NONPRIMARY HIGHWAYS — MAXIMUM GROSS WEIGHT TABLE
Distance
in feet 2 Axles 3 Axles 4 Axles 5 Axles 6 Axles7 Axles
4 34,000
5 34,000
6 34,000
7 34,000 34,000
8 34,000 34,000
8’1” 38,000 42,000
9 39,000 42,500
10 40,000 43,500 45,000
11 44,000 46,000
12 45,000 47,000
13 45,500 48,000 48,500
14 46,500 49,000 49,500
15 47,000 50,000 50,500
16 48,000 51,000 51,500
17 48,500 52,000 52,500 54,000
18 49,500 53,000 53,500 55,000
19 50,000 54,500 54,500 56,000
20 51,000 55,500 55,500 57,000
21 51,500 56,000 56,500 58,000
22 52,500 56,500 57,500 59,000
23 53,000 57,500 58,500 60,000
24 54,000 58,000 59,500 61,000
25 54,500 58,500 60,500 62,000
26 55,500 59,500 61,500 63,000
27 56,000 60,000 62,500 64,000
28 57,000 60,500 63,500 65,000
29 57,500 61,500 64,500 66,000
30 58,500 62,000 65,500 67,000
31 59,000 62,500 66,500 68,000
32 60,000 63,500 67,500 69,000
33 64,000 68,500 70,000
34 64,500 69,500 71,000
35 65,500 70,000 72,000
36 68,000 70,500 73,000
37 68,000 71,000 74,000
38 68,000 72,000 75,000
39 68,000 72,500 76,000
40 68,500 73,000 77,000
41 69,500 73,500 78,00078,000
42 70,000 74,000 79,00079,000
43 70,500 75,000 80,00080,000
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
c. (1) The maximum gross weight allowed to be carried on a commercial motor vehicle on noninterstate highways, provided the vehicle is operated by a person with a commercial driver’s license valid for the vehicle operated unless section 321.176A applies, is as follows:
NONINTERSTATE HIGHWAYS
MAXIMUM GROSS WEIGHT TABLE
COMMERCIAL MOTOR VEHICLE
Distance in feet 6 Axles 7 Axles
44 80,500 80,500
45 81,000 81,500
46 81,500 82,500
47 82,000 83,500
48 83,000 84,000
49 83,500 85,000
50 84,000 86,000
51 84,500 87,000
52 85,000 88,000
53 86,000 88,500
54 86,500 89,500
55 87,000 90,500
56 87,500 91,500
57 88,000 92,000
58 89,000 93,000
59 89,500 94,000
60 90,000 95,000
61 95,500
62 96,000
(2) Notwithstanding any provision of this section to the contrary, the maximum gross weight allowed to be carried on a noninterstate highway by a livestock vehicle with five axles, a minimum distance in feet between the centers of the first and fifth axles of sixty-one feet, and a minimum distance between the two rear axles of at least eight feet and one inch is eighty-six thousand pounds.
d. For the purposes of the maximum gross weight tables in paragraphs “a”, “b”, and “c”, distance in feet is the measured distance in feet between the centers of the extreme axles of any group of axles, rounded to the nearest whole foot.
e. (1) The maximum gross weight allowed to be carried on a tracked implement of husbandry when operated on a noninterstate highway bridge is as follows:
NONINTERSTATE HIGHWAY BRIDGES
MAXIMUM GROSS WEIGHT TABLE
TRACKED IMPLEMENTS OF HUSBANDRY
Length of Track in Feet Weight in Pounds
4 34,000
5 34,000
6 34,000
7 34,000
8 42,000
9 42,500
10 45,000
11 46,000
12 47,000
13 48,500
14 49,500
15 50,500
16 51,500
17 54,000
18 55,000
19 56,000
20 57,000
21 58,000
22 59,000
23 60,000
24 61,000
25 62,000
26 63,000
27 64,000
28 65,000
29 66,000
30 67,000
31 68,000
32 69,000
33 70,000
34 71,000
35 72,000
36 73,000
37 74,000
38 75,000
39 76,000
40 77,000
41 78,000
42 79,000
43 80,000
(2) “Length of track in feet” means the length of track on one side of the tracked implement of husbandry which is in contact with the ground or roadway surface.
7. The weight on any one axle, including a tandem axle, of a vehicle which is transporting livestock on highways not part of the interstate system may exceed the legal maximum weight given in this chapter providing that the gross weight on any particular group of axles on such vehicle does not exceed the gross weight allowable under this chapter for such groups of axles.
8. The weight on any one axle, including a tandem axle, of a vehicle which is transporting raw materials from a designated borrow site to a construction project or transporting raw materials from a construction project, and which is operating on a highway that is not part of the interstate system and along a route of travel approved by the department or the appropriate local authority, may exceed the legal maximum weight otherwise allowed under this chapter by ten percent if the gross weight on any particular group of axles on the vehicle does not exceed the gross weight allowed under this chapter for that group of axles. If the vehicle exceeds the ten percent tolerance allowed under this subsection, the fine shall be computed on the difference between the actual weight and the ten percent tolerance weight allowed for the axle or tandem axle.
9. A vehicle or combination of vehicles transporting materials or equipment on nonprimary highways to or from a construction project or commercial plant site may operate under the maximum gross weight table for primary highways in subsection 6, paragraph “a”, or the maximum gross weight table for noninterstate highways in subsection 6, paragraph “c”. When crossing a bridge, such a vehicle or combination of vehicles shall comply with any weight restriction imposed for the bridge pursuant to section 321.471 or 321.474, provided signs that conform to the manual of uniform traffic-control devices adopted by the department that give notice of the restriction are posted as required under section 321.472 or 321.474, as applicable.
10. A vehicle designed to tow wrecked or disabled vehicles shall be exempt from the weight limitations in this section while the vehicle is towing a wrecked or disabled vehicle.
11. a. A person who operates a vehicle in violation of this section, and an owner, or any other person, employing or otherwise directing the operator of a vehicle, who requires or knowingly permits the operation of a vehicle in violation of this section shall be fined according to the following schedule:
AXLE, TANDEM AXLE, AND GROUP OF AXLES
WEIGHT VIOLATIONS
Pounds Overloaded Amount of Fine
Up to and including 1,000 pounds $12
Over 1,000 pounds up to and
including 2,000 pounds $22
Over 2,000 pounds up to and
including 3,000 pounds $155
Over 3,000 pounds up to and
including 4,000 pounds $240
Over 4,000 pounds up to and
including 5,000 pounds $375
Over 5,000 pounds up to and
including 6,000 pounds $585
Over 6,000 pounds up to and
including 7,000 pounds $850
Over 7,000 pounds up to and
including 8,000 pounds $950
Over 8,000 pounds up to and
including 9,000 pounds $1,050
Over 9,000 pounds up to and
including 10,000 pounds $1,150
Over 10,000 pounds up to and
including 11,000 pounds $1,300
Over 11,000 pounds up to and
including 12,000 pounds $1,400
Over 12,000 pounds up to and
including 13,000 pounds $1,500
Over 13,000 pounds up to and
including 14,000 pounds $1,600
Over 14,000 pounds up to and
including 15,000 pounds $1,700
Over 15,000 pounds up to and
including 16,000 pounds $1,800
Over 16,000 pounds up to and
including 17,000 pounds $1,900
Over 17,000 pounds up to and
including 18,000 pounds $2,000
Over 18,000 pounds up to and
including 19,000 pounds $2,100
Over 19,000 pounds up to and
including 20,000 pounds $2,200
Over 20,000 pounds $2,200 plus ten cents
per pound in excess
of 20,000 pounds
b. Fines for gross weight violations for vehicles or combinations of vehicles shall be assessed at one-half of the fine rate schedule for axle, tandem axle, and groups of axles weight violations.
c. Except as otherwise provided, the amount of the fine to be assessed shall be computed on the difference between the actual weight and the maximum legal weight specified in this section.
d. The schedule of fines may be assessed in addition to any other penalties provided for in this chapter.
12. Overloads on axles and tandem axles and overloads on groups of axles or on an entire vehicle or combination of vehicles shall be considered as separate violations of the provisions of this section.
13. A person shall not issue or execute, or cause to be issued or executed, a bill of lading, manifest, or shipping document of any kind which states a false weight of the cargo set forth on such bill, manifest, or document, which is less than the actual weight of the cargo.
14. a. A person operating a vehicle or combination of vehicles equipped with a retractable axle may raise the axle when necessary to negotiate a turn, provided that the retractable axle is lowered within one thousand feet following completion of the turn. This paragraph does not apply to a vehicle or combination of vehicles operated on an interstate highway, including a ramp to or from an interstate highway, or on a bridge.
b. A vehicle or combination of vehicles operated with a retractable axle raised as permitted under paragraph “a” is exempt from the weight limitations of this section as long as the vehicle or combination of vehicles is in compliance with the weight limitations of this section when the retractable axle is lowered.
c. This subsection does not prohibit the operation of a vehicle or combination of vehicles equipped with a retractable axle with the retractable axle raised when the vehicle or combination of vehicles is in compliance with the weight limitations of this section with the retractable axle raised.
15. A person who violates this section commits a simple misdemeanor.
[C24, 27, 31, 35, §5065; C39, §5035.12; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §321.463; 81 Acts, ch 110, §1, ch 111]
89 Acts, ch 200, §1, 2; 92 Acts, ch 1238, §35; 94 Acts, ch 1199, §79; 95 Acts, ch 118, §26; 96 Acts, ch 1089, §4; 97 Acts, ch 100, §5, 12; 97 Acts, ch 104, §22; 98 Acts, ch 1103, §2; 98 Acts, ch 1178, §6, 7; 99 Acts, ch 108, §7; 2000 Acts, ch 1016, §17; 2000 Acts, ch 1040, §1; 2001 Acts, ch 32, §23 – 25; 2002 Acts, ch 1063, §33, 55; 2005 Acts, ch 20, §5 – 7, 12, 13; 2007 Acts, ch 143, §17; 2009 Acts, ch 133, §121; 2010 Acts, ch 1139, §1; 2010 Acts, ch 1140, §16, 17; 2013 Acts, ch 27, §1; 2013 Acts, ch 140, §62; 2017 Acts, ch 29, §96; 2017 Acts, ch 149, §2; 2018 Acts, ch 1172, §73; 2019 Acts, ch 15, §1; 2019 Acts, ch 138, §3; 2019 Acts, ch 158, §1; 2020 Acts, ch 1063, §152; 2021 Acts, ch 140, §1, 4
Referred to in §312.2, 321.453, 321.457, 321.459, 321.466, 321.473, 321E.2, 321E.7, 321E.8, 321E.9, 321E.9A, 321E.16, 321E.17, 321E.26, 321E.27, 321E.29, 321E.29A, 321E.29B, 321E.30, 805.8A(12)(e)
For scheduled fines listed in subsection 11, violations are charged and fines are applied pursuant to §805.8A, subsection 12, paragraph e
2021 amendment to subsection 3 effective January 1, 2022; 2021 Acts, ch 140, §4
Subsection 3 amended

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