761—511.15(321,321E) Maximum axle weights and maximum gross weights for vehicles and loads moved under permit.
	511.15(1) Annual and all-systems permits.
	a. 	For movement under an annual or all-systems permit, the axle weight and combined gross weight shall not exceed the limits found in Iowa Code section 321.463(3).
	b. 	See subrule 511.15(6) for exceptions for special mobile equipment.
	511.15(2) Annual oversize/overweight permits or annual raw forest products permits.
	a. 	For movement under an annual oversize/overweight permit or an annual raw forest products permit, the gross weight on any axle shall not exceed 20,000 pounds, with a maximum of 156,000 pounds total gross weight.
	b. 	See subrule 511.15(6) for exceptions for special mobile equipment.
	511.15(3) Multitrip permits.
	a. 	For movement under a multitrip permit, the gross weight on any axle shall not exceed 20,000 pounds with a maximum of 156,000 pounds total gross weight.
	b. 	See subrule 511.15(6) for exceptions for special mobile equipment.
	511.15(4) Single-trip permits.
	a. 	For movement under a single-trip permit, the gross weight on any axle shall not exceed 20,000 pounds.
	b. 	If the combined gross weight exceeds 100,000 pounds, a single-trip permit may be issued for the movement only if the permit-issuing authority determines that it would not cause undue damage to the road and is in the best interest of the public.
	c. 	Cranes may have a maximum of 24,000 pounds per axle for movement under a single-trip permit. Routes must be reviewed by the permit-issuing authority prior to issuance.
	d. 	See subrule 511.15(6) for exceptions for special mobile equipment.
	511.15(5) Emergency interstate permits.
	a. 	For movement under this permit, the gross weight on any axle shall not exceed 20,000 pounds with a maximum of 90,000 pounds total gross weight.
	b. 	The maximum weight on any single axle shall not exceed by more than 12.5 percent the maximum axle weight limit in the nonprimary highway maximum gross weight table in Iowa Code section 321.463(6)“b” and must comply with posted limits on roads and bridges.
	511.15(6) Special mobile equipment. Special mobile equipment may have a gross weight of 36,000 pounds on any single axle equipped with minimum size 26.5-inch by 25-inch flotation pneumatic tires and a maximum gross weight of 20,000 pounds on any single axle equipped with minimum size 18-inch by 25-inch flotation pneumatic tires, provided that the total gross weight of the vehicle or a combination of vehicles does not exceed a maximum of 80,000 pounds for movement under an annual or all-systems permit and 126,000 pounds for movement under a single-trip, multitrip or annual oversize/overweight permit.
For tire sizes and weights allowed between the maximum and minimum indicated, the following formula shall apply: Axle weight = 20,000 pounds + (tire width - 18) × 1,882 pounds.
	511.15(7) Permitted tandem axle weights.
	a. 	Vehicles operating under an annual oversize permit, annual oversize/overweight permit, annual raw forest products permit, single-trip permit, or multitrip permit may have a gross weight not to exceed 46,000 pounds on a single-tandem axle of the truck tractor and a gross weight not to exceed 46,000 pounds on a single-tandem axle of the trailer or semitrailer if each axle of each tandem group has at least four tires.
	b. 	The maximum weight of any single axle within a permitted tandem axle group shall be 24,000 pounds.
	c. 	A permitted tandem axle shall not be a part of a larger group of axles whose centers are greater than 96 inches apart.
This rule is intended to implement Iowa Code sections 321.463, 321E.7, 321E.8, 321E.9, 321E.9A, 321E.26, 321E.29B as enacted by 2021 Iowa Acts, House File 382, and 321E.32.
[ARC 3193C, IAB 7/5/17, effective 8/9/17; ARC 4345C, IAB 3/13/19, effective 4/17/19; ARC 4985C, IAB 3/11/20, effective 4/15/20; ARC 6061C, IAB 12/1/21, effective 1/5/22]