Alaska Axle Weight Limits

Maximum Legal Weight Allowed

For a vehicle or combination of vehicles, including load and equipment, the weight on axles or axle groups may not exceed, and the distance between axles may not be less than, the following: 

• The weight on a tire may not exceed 600 pounds per linear inch of tire width based upon the tire manufacturer's rating of nominal tire width;
• Single Axle, 8'1" Minimum spacing* - 20,000 pounds;
• 2-Axle Group, 3'6" Minimum spacing - 38,000 pounds;
• 3-Axle Group, 3'6" Minimum spacing - 42,000 pounds;
• 4-Axle Group, 3'6" Minimum spacing - 50,000 pounds.

* Any axle spaced less than 8 feet and 1 inch from any other axle, measured between the centers of the nearest axles, is considered as part of an axle group. In multi-axle groups, all axles must carry at least 6,000 pounds if the axle group is more than 50 percent of the legal group weight. Lift axles or variable suspension axles are allowed in the drive axle group of the power vehicle, but may not be used to determine the legal allowable vehicle gross weight prescribed by the Bridge Gross Weight Formulas.

If the combination of a track-tractor and single semitrailer combination where the length of the semitrailer is 48 feet or more, the weight on a three-axle group on the semitrailer may not exceed, and the distance between the axles may not be less than the following:

• 3'6' Minimum spacing - 42,000 pounds;
• 5' Minimum spacing - 43,500 pounds;
• 6' Minimum spacing - 45,000 pounds. 

The maximum gross vehicle weight for a vehicle with lift axles in the drive axle group may not be greater than the weight determined under the following formula:

W = 500 (LN/(N-1) + 12N + 36),

Where:

The maximum gross vehicle weight for a vehicle with no lift axles in the drive axle groups may not be greater than the weight determined under the following formula:

W = 500 (LN/(N-1) + 12N +36) +3,000,

Where:

In a combination of a power vehicle and two or more cargo-carrying vehicles consisting of trailers and semitrailers, the heavier cargo-carrying vehicle must be placed immediately behind the power vehicle when one cargo-carrying vehicle is more than 5,000 pounds heavier than any other cargo-carrying vehicle in the combination. The weight of the power and the first cargo-carrying vehicle in a combination with two or more cargo-carrying vehicles may not exceed the weight allowable in this section for a power vehicle and single cargo carrying vehicle with the same axle configuration and of equal length, calculated without regard to the weight of the following cargo-carrying vehicles in the combination. 

The weight carried by individual axle groups before or after pintle hooks or other connecting devices in vehicle combinations may not exceed the standards for axle group weights.

Between October 1 and March 31, shifting of legal axle weights is allowed for one, two, and three drive axle groupings on power vehicles traveling on the Steese, Elliot, Dalton, and Richardson Highways between North Pole and Prudhoe Bay, or between North Pole and MP 30 of the Steese Highway. The shifted weight on these drive axle groupings may not exceed 2,000 pounds per axle. The legal allowable gross weight on a vehicle or combination of vehicles may not exceed the maximum weight as determined by methods. An overweight permit is not required for shifting additional weight to the drive axle group during the period defined. Traction weight shifting is not allowed for a power vehicle traveling under an overweight permit. Vehicle combinations operating with traction-weight shifting on the power vehicle will be allowed reasonable right of acess to and from the Steese, Elliott, and Dalton Highways, when traveling between Fairbanks and Prudhoe Bay, to reach or return from terminals and facilities for food, fuel, and rest, if the vehicle uses the most direct route between North Pole and Fox. All movement within organized municipalities and boroughs is subject to local ordinances in addition to the requirements of this chapter.

Except when an emergency requires immediate action, if the department determines that a highway may be damaged by a vehicle's weight, weight restrictions may be imposed after appropriate notice has been given to the public. When weight restrictions are imposed, they will be stated as a percentage of the legal allowable axle weights and applied to the maximum axle loading. The weight on steering axles may not be restricted below 100 percent of the legal allowable axle weight. Unless approved by the department, a permit issued under 17 AAC 25.320 allowing overweight vehicles does not satisfy the requirements of this chapter in order to travel on weight-restricted highways during period when weight restrictions are imposed.

"Pounds per inch of tire width" is determined by dividing the sum of the tire width in inches for tire mounted on an axle group into the weight carried on that axle group in pounds. 

A vehicle subject to the provisions of this section that uses an auxiliary power unit or an idle reduction technology unit in order to promote reduction of fuel use and emissions because of engine idling, will be allowed up to an additional 550 pounds total in power unit axle weights, gross vehicle weights, or bridge formula weight limits. Certification of the weight of the auxiliary power unit must be available to law enforcement officers if the vehicle is found in violation of applicable weight laws. the additional weight allowed may not exceed 550 pounds or the weight certified, whichever is less. To be eligible for this exception, the operator of the vehicle must be able to prove by

1. written certification, the weight of the auxiliary power unit or idle reduction technology unit; and
2. demonstration or certification, that the auxiliary power unit or idle reduction technology unit is fully functional at all times.

Maximum Permit Weight Allowed

Permits are issued on the premise that the legal length and weight of the load described has been reduced to the smallest practical size. Permits will not be issued if weight can be reduced to legal limits by repositioning and/or practical removal of a part, portion, unit, or other appurtenance, so as to minimize the overweight condition. 

Overweight vehicle or vehicle with load permits up to 125 percent of legal allowable weight (legal axle, axle group, or gross weight) may be issued without further checking of bridge conditions. 

• Single Axle - 25,000 lbs. maximum;
• Tandem Axle - 47,500 lbs. maximum;
• Tridem Axle - 52,500 lbs. maximum; 
• Quadrum Axle - 62,500 lbs. maximum. 

Source of information: http://www.dot.state.ak.us/mscve/assets/webdocs/permits_manual.pdf
http://www.dot.skate.ak.us/mscve/webdocs/17AAC25.pdf