Truck Weight Limits and Axle Regulations in Wyoming

Wyoming establishes its commercial vehicle weight regulations under Wyoming Statute § 31-18-802, which is enforced by the Wyoming Department of Transportation (WYDOT) and the Wyoming Highway Patrol. The state permits a maximum gross vehicle weight (GVW) of 80,000 pounds on the Interstate system (I-25, I-80, and I-90) without a permit, provided the vehicle complies with the federal bridge formula. However, on non-interstate highways, Wyoming allows for higher weight thresholds reaching up to 117,000 pounds for specific multi-axle configurations, provided they meet the internal spacing requirements defined in the state's weight table. Carriers must distinguish between these two road systems to avoid citations that scale based on the degree of the overweight violation. Maintaining compliance requires precise route planning that accounts for varying load ratings on secondary state highways and aging bridge structures. DispatchTool assists owner-operators by providing truck-safe routing that incorporates these specific WYDOT weight restrictions and bridge heights into every dispatch. By identifying restricted routes before the driver departs, the platform reduces the risk of expensive fines or forced offloads at Wyoming ports of entry. To begin managing your Wyoming routes and permit documents in one interface, you can create a DispatchTool account.

Standard Legal Weight Limits and Axle Maximums

According to WYDOT, the maximum weight allowed on a single axle is 20,000 pounds, while a tandem axle set is limited to 36,000 pounds. A triple axle configuration (tridem) is allowed up to 42,000 pounds, depending on the spacing between the centers of the axles. For the gross vehicle weight to reach the 80,000-pound cap on Interstates, the distance between the first and last axles must be at least 51 feet. Tire pressure limitations also apply, where no tire may exceed 600 pounds per inch of tire width. These figures are strictly enforced at the 14 permanent ports of entry located at state borders.

Wyoming Bridge Formula and Table I Calculations

Wyoming uses a specific calculation known as 'Table I' to determine allowable weights on non-interstate highways. This table allows for a maximum of 117,000 pounds for vehicles with seven or more axles and a wheelbase of at least 72 feet. The state's formula, W = 500 [LN/(N-1) + 12N + 36], where 'W' is weight, 'L' is length in feet, and 'N' is the number of axles, is applied to all groups of two or more consecutive axles. Compliance ensures that the weight distribution does not exceed the structural capacity of the 3,100+ bridges maintained by the state. Drivers must measure the distance between the centers of the extreme axles to the nearest foot to ensure their specific configuration is legal for the intended route.

Overweight Permit Types and Costs

For loads exceeding 80,000 pounds on Interstates or 117,000 pounds on secondary roads, carriers must obtain an overweight permit from the WYDOT Overweight/Oversize office. A single-trip overweight permit typically costs $0.06 per ton-mile for the excess weight, with a minimum fee of $40.00. For loads that are over-width or over-height in addition to being overweight, additional fees apply. Wyoming also offers an 'Annual Overweight' permit for specific configurations that do not exceed 117,000 pounds and follow designated routes, which costs $500.00 per year. Permits must be carried in the cab, either in paper form or as a digital copy, and presented at port-of-entry inspections.

Seasonal Weight Restrictions and Closures

Wyoming experiences significant freeze-thaw cycles that impact pavement durability. WYDOT may implement temporary 'Spring Break-up' weight restrictions on secondary highways, often reducing allowable axle weights by 20% to 50% to prevent road surface damage. These restrictions are typically posted with temporary signage and updated on the 511 WYDOT road condition map. Furthermore, I-80 is frequently subjected to high wind closures where vehicles with a high profile or light weights (typically under 40,000 lbs GVW) are prohibited from travel. Failure to obey these temporary weight or weather-related restrictions results in a minimum fine of $200 plus court costs.

Enforcement and Penalties for Overweight Violations

Overweight penalties in Wyoming are calculated based on the number of pounds over the legal limit. Per Wyoming Statute § 31-18-805, a violation of 1,000 to 2,000 pounds over the limit results in a $55 fine, but this escalates sharply. If a vehicle is more than 10,000 pounds overweight, the fine is $750 plus $0.10 for each pound in excess of 10,000 pounds. Additionally, the driver may be required to shift the load to become legal or offload the excess weight at a safe location before proceeding. Repeated violations within a 12-month period can lead to the suspension of the carrier's ability to pull overweight permits in the state.

Port of Entry Requirements

Wyoming is a 'mandatory port' state. All commercial vehicles must stop at the first available Port of Entry when entering the state, regardless of whether they have a PrePass or similar weigh-station bypass system, unless they have received a green light signal specifically for that location. At the port, officials verify the vehicle's registration, IFTA credentials, and actual weight against the declared weights. Wyoming operates ports 24/7 in high-traffic areas like Cheyenne, Evanston, and Gillette. If a port is closed, the driver must continue until they reach an open port or their destination, keeping records of their route and weights to prove compliance if stopped by mobile enforcement.

Special Exemptions for Agriculture and Livestock

Agricultural producers and livestock haulers in Wyoming may qualify for specific weight exemptions during harvest seasons. Under certain conditions, vehicles hauling primary agricultural products from the field to a storage or processing facility may exceed legal axle weights by up to 10%, provided the GVW does not exceed 80,000 pounds on the Interstate. However, these exemptions do not apply to the Federal Bridge Formula on Interstate highways unless a specific disaster emergency has been declared by the Governor. Livestock haulers are encouraged to utilize the 'Live Load' priority at ports to minimize stationary time, though they must still meet all Bridge Formula requirements to ensure safety on mountain passes.

Sources

Wyoming Department of Transportation (WYDOT) (2024) — http://www.dot.state.wy.us/home/trucking_commercial_vehicles/oversize_overweight_permits.html Wyoming State Statutes (2023) — https://wyoleg.gov/statutes/compress/title31.pdf Federal Highway Administration (FHWA) (2024) — https://ops.fhwa.dot.gov/freight/sw/brdgcalc/index.htm

Frequently asked

What is the maximum weight for a tandem axle in Wyoming?

The maximum legal weight for a tandem axle in Wyoming is 36,000 pounds, provided the axles are spaced more than 40 inches but no more than 96 inches apart.

How much does an overweight permit cost in Wyoming?

A single-trip overweight permit has a minimum fee of $40, but the total cost is calculated at $0.06 per ton-mile for the weight exceeding legal limits.

Does Wyoming allow 129,000-pound loads?

Yes, Wyoming allows 'Longer Combination Vehicles' (LCVs) to weigh up to 117,000 pounds on state roads regularly, and up to 129,000 pounds on specific routes with a special permit and a vehicle configuration containing at least 9 axles.

Are there weight limits for the steering axle?

Wyoming limits the steering axle to a maximum of 20,000 pounds or the manufacturer's rated capacity, whichever is less, though it must also comply with the 600 pounds per inch of tire width rule.

Is the Federal Bridge Formula used in Wyoming?

Yes, Wyoming applies the Federal Bridge Formula (Formula B) to all vehicles operating on the Interstate system to protect the national highway infrastructure.