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New Hampshire Axle Weight Limits

Axle spacings and weight calculator

Max Legal Weight for GVW under 80,000 lbs and Max Permitted Weight for GVW over 80,000 lbs

Vehicle configuration

Maximum Legal Weight Allowed

Axle Group 



22,400 pounds on all vehicles w/axles 10’ or more apart (including combination vehicles) except as noted for 4-axle single unit vehicles.


18,000 pounds/axle on all vehicles except for 3 and 4 axle single unit vehicles.


For combination of tractor-trailer and single semi-trailer w/ 4 or more axles.

Maximum on tandem: 36,000 pounds

Maximum on tridem: 54,000 pounds

Gross Vehicle Weight                                                                             

80,000 pounds

Two Axle Truck – 33,400 lbs.
Three Axle Truck – 55,000 lbs., 22,400 lbs./axle max 
Four Axle Truck – 60,000 lbs., 18,000 lbs./axle

Maximum Permit Weight Allowed

Maximum Certified Vehicle Weight Limits on Approved Structures:

Single Unit Vehicles:

Two Axle Truck – 37,400 lbs.
Three Axle Truck – 65,000 lbs., 22,400 lbs./axle max
Four Axle Truck – 73,000 lbs., 20,000 lbs./axle

Combination Vehicles:

3 Axle Tractor Semi-Trailer – 54,500 – 60,000 lbs. (D=25 ft. – 32 ft.)
4 Axle Semi-Trailer – 59,000 – 69,000 (D = 8 ft. – 18 ft.)
5 or 6 Axle Semi-Trailer – 70,000 – 84,000 lbs. (D=19 ft. – 29 ft.)
86,000 – 99,000 lbs. (D = 30 ft. – 36 ft.)
6,7 or 8 Axle Semi-Trailer – 86,000 – 99,000 lbs. (D=30 ft. – 36 ft.)

OS/OW Permit shall be submitted to Bridge Design for bridge review if:

Any bridge on the proposed route has a load posting or weight restriction
Any axle spacing less than 4'-0"
Any single axle exceeds 27,500 pounds. (10'-0" or more to any adjacent axle)
Any axle of a tandem group exceeds 25,000 pounds. (see note 2)
Any axle of a tridem group exceeds 22,500 pounds. (see note 2)
Any axle of a quad group exceeds 20,000 pounds. (see note 2)
Any group of five axles. (see note 2)
Any 2-Axle Single Unit exceeds 55,000 pounds.
Any 3-Axle Single Unit exceeds 72,500 pounds.
Any 4-Axle Single Unit exceeds 90,000 pounds.
Any 5-Axle Single Unit exceeds 100,000 pounds.
Any Single Unit, with 6 or more axles, exceeds 110,000 pounds.
Any 3-Axle Combination Unit exceeds 82,500 pounds.
Any 4-Axle Combination Unit exceeds 95,000 pounds.
Any 5-Axle Combination Vehicle exceeds 108,000 pounds.
Any 6-Axle Combination Vehicle exceeds 120,000 pounds.
Any 7-Axle Combination Vehicle exceeds 130,000 pounds.
Any Combination Vehicle, with 8 or more axles, exceeds 149,999 pounds.

Note 1) RSA 266:18-c states that a vehicle or combination of vehicles shall not be driven or moved over any bridge or other structure on any way if the weight of such vehicle, or combination of vehicles and load, is greater than the capacity of the structure as shown by a sign on the right side of or overhead on the structure. It is assumed that the weight of the OS/OW permit vehicle will be in excess of the provisions of RSA 266:18-b, and therefore will exceed the posted capacity of the bridge.

Note 2) For purposes of this table, axles together are considered a group of axles (tandem, tridem, quad, etc.) when each individual axle space in the group is less than 10'-0".

Note 3) Speed of permit vehicle shall not exceed 20 miles per hour while crossing bridges (except for bridges on the interstate and turnpike system, or corridors designed to meet interstate standards...including NH101 from Manchester to Hampton, etc.).

Source of information: