In 1975, the U.S. Congress enacted the bridge formula to limit the weight-length ratio of a vehicle crossing a bridge. This is done by increasing the distance between axels or by spreading weight over additional axles. The reason for the formula is because, during the 1950s and 1960s, trucks grew heavier and began putting too much strain on bridges on the interstate highways.
The bridge formula is calculated by multiplying the distance in feet between the outer axles of any group of two or more consecutive axles by the number of axles in the group under consideration. This number is then divided by the number of axles in the group under consideration minus one. After getting this quotient, add 36 and the product of 12 times the number of axles in the group under consideration to the quotient. This final number is then multiplied by 500 to get the overall gross weight on any group of two or more consecutive axles to the nearest 500 pounds.
In addition to the bridge formula weight limits, federal law states that gross weight vehicle is limit to 80,000 pounds. States have given exemptions to different types of vehicles to operate above the standard federal truck size and weight limits. This exemption often only applies to non-Interstate highways.
Below is each state’s maximum gross weight limit. Each state’s interstate limit is 80,000 lbs. unless exempt or indicated that longer combination vehicles (LCV) are exempt.
Alabama
- 84,000 lbs. on 6 axles
Alaska
- Up to 145,000 lbs. on 11 axles
- Exempt from the interstate weight limit
Arizona
- 80,000 lbs.
- Longer combination vehicles (LCV) exempt from the interstate limit
Arkansas
- 80,000 lbs.
California
- 80,000 lbs.
Colorado
- 85,000 lbs.
- Longer combination vehicles (LCV) exempt from the interstate limit
Connecticut
- 80,000 lbs.
Delaware
- 80,000 lbs. on 5 axles
District of Columbia
- 80,000 lbs.
Florida
- 80,000 lbs.
Georgia
- 80,000 lbs.
Hawaii
- 88,000 lbs.
Idaho
- 105,500 on 6 axles
- Longer combination vehicles (LCV) exempt from the interstate weight limit
Illinois
- 73,280 lbs. on non-national highways
Indiana
- 80,000 lbs.
- Longer combination vehicles (LCV) exempt from the interstate weight limit
Iowa
- 80,000 lbs.
Kansas
- 85,500 lbs.
- Longer combination vehicles (LCV) exempt from the interstate weight limit
Kentucky
- 80,000 lbs.
Louisiana
- 88,000 lbs. tri or quad axle
Maine
- 90,000 lbs.
Maryland
- 80,000 lbs.
Massachusetts
- 80,000 lbs.
Michigan
- 164,000 lbs. on 11 axles
Minnesota
- 80,000 lbs. on 6 axles
Mississippi
- 80,000 lbs. (57,650 on highway class)
Missouri
- 73,280 lbs. (2,000 tolerance)
- Longer combination vehicles (LCV) exempt from the interstate weight limit
Montana
- 80,000 lbs.
- Longer combination vehicles (LCV) exempt from the interstate weight limit
Nebraska
- 95,000 on 7 axles
Nevada
- Uncapped
- Longer combination vehicles (LCV) exempt from the interstate weight limit
New Hampshire
- 80,000 lbs.
New Jersey
- 80,000 lbs.
New Mexico
- 86,400 lbs.
New York
- 80,000 lbs.
North Carolina
- 80,000 lbs.
North Dakota
- 105,500 lbs. on 7 axles
- Longer combination vehicles (LCV) exempt from the interstate weight limit
Ohio
- 80,000 lbs.
- Longer combination vehicles (LCV) exempt from the interstate weight limit
Oklahoma
- 90,000 lbs.
- Longer combination vehicles (LCV) exempt from the interstate weight limit
Oregon
- 80,000 lbs.
- Longer combination vehicles (LCV) exempt from the interstate weight limit
Pennsylvania
- 80,000 lbs.
Rhode Island
- 80,000 lbs.
South Carolina
- 80,000 lbs.
South Dakota
- Uncapped
- Longer combination vehicles (LCV) exempt from the interstate weight limit
Tennessee
- 80,000 lbs.
Texas
- 80,000 lbs.
Utah
- 80,000 lbs.
- Longer combination vehicles (LCV) exempt from the interstate weight limit
Vermont
- 80,000 lbs.
Virginia
- 80,000 lbs.
Washington
- 80,000 lbs.
West Virginia
- 65,000 lbs. (73,500 lbs. on some highways)
Wisconsin
- 80,000 lbs.
Wyoming
- 117,000 on 8 axles