Truck Weight Limits and Regulations in Utah

The Utah Department of Transportation (UDOT) and the Utah Highway Patrol (UHP) enforce specific weight limits to protect the state’s 46,000 lane miles of highway and bridge infrastructure. Under Utah Code § 72-7-404, the maximum gross vehicle weight for a standard tractor-trailer configuration is 80,000 pounds on the Interstate System, unless the vehicle is operating under a valid overweight permit. These limits are calculated based on the Federal Bridge Formula, which considers the number of axles and the distance between them to ensure load distribution does not exceed the structural capacity of the pavement. Motor carriers must maintain strict compliance to avoid significant fines and safety interventions. DispatchTool helps carriers stay compliant by providing truck-safe routing that accounts for Utah’s specific bridge weight restrictions and state-maintained highway constraints. By integrating these weight parameters into the route planning process, dispatchers can ensure drivers avoid restricted routes and costly citations. To streamline your compliance and routing operations, you can create a DispatchTool account to access Utah-specific trucking data.

Standard Weight Limits and Axle Distributions

Utah adheres to federal standards for axle weight limits on all Interstate and primary highways. A single axle is limited to 20,000 pounds, while a tandem axle set (spaced between 40 and 96 inches) is limited to 34,000 pounds. For vehicles operating on the Interstate System, the gross vehicle weight (GVW) cannot exceed 80,000 pounds without a permit. However, Utah allows for higher weights on non-Interstate highways through the LCV (Long Combination Vehicle) program, provided the vehicle meets specific bridge formula requirements. Steering axles are typically limited to 600 pounds per inch of tire width or a maximum of 20,000 pounds, whichever is less, per UDOT Rule R909-2.

The Federal Bridge Formula in Utah

Utah strictly applies the Federal Bridge Formula B to determine the maximum weight any group of two or more consecutive axles may carry. The formula, W = 500 [LN / (N-1) + 12N + 36], where L is the distance in feet between the extremes of any group of axles and N is the number of axles in the group, is used to prevent bridge stress. For example, a five-axle tractor-trailer with a 51-foot wheelbase can carry the full 80,000-pound GVW, but shorter configurations may be restricted to lower weights even if they do not exceed axle limits. UDOT uses this calculation to evaluate permit applications for loads exceeding 80,000 pounds.

Overweight Permits and Fee Schedules

If a load is non-divisible and exceeds 80,000 pounds, a carrier must obtain an overweight permit from the UDOT Motor Carrier Division. Single-trip permits for weights up to 125,000 pounds generally cost $60 plus $0.06 per ton-mile for any weight exceeding 80,000 pounds. For frequent operations, carriers can purchase an annual overweight permit for $500, provided the vehicle does not exceed 129,000 pounds GVW. All permitted vehicles must follow specific routes designated by the state and may be subject to time-of-day travel restrictions in high-traffic areas like Salt Lake County and Utah County.

Utah LCV and 129,000 Pound Configurations

Utah is one of several western states that allows Long Combination Vehicles (LCVs) to operate at weights up to 129,000 pounds on designated routes. These configurations, such as Rocky Mountain Doubles or Turnpike Doubles, require a specialized LCV permit. The trailers in a Rocky Mountain Double configuration typically consist of one 48-foot trailer and one 28.5-foot trailer. To qualify for the 129,000-pound limit, the vehicle must have a minimum of nine axles and meet the bridge formula requirements for the entire length of the combination. Drivers operating these units must possess a doubles/triples endorsement on their CDL.

Enforcement and Overweight Penalties

The Utah Highway Patrol (UHP) operates 12 fixed port-of-entry stations and utilizes mobile weigh-in-motion (WIM) technology to monitor compliance. Under Utah Code § 72-7-407, fines for overweight violations are calculated on a graduated scale based on the number of pounds over the limit. For example, being 2,001 to 5,000 pounds overweight can result in a fine of approximately $100 plus surcharges, while exceeding the limit by more than 10,000 pounds can result in fines exceeding $1,000. In addition to fines, UHP may require the driver to shift the load or offload excess weight before the vehicle is allowed to leave the scale house.

Tire and Wheel Load Requirements

Utah regulations specify that the weight exerted on the road surface by any wheel cannot exceed 10,500 pounds. Furthermore, the weight per inch of tire width is capped at 600 pounds. This is particularly relevant for heavy specialized hauling where wide-base 'super single' tires are used. If a vehicle's tire width is insufficient for the load, it may be found in violation even if the total axle weight is below the 20,000 or 34,000-pound threshold. UDOT inspectors measure tire tread width at the point of contact with the road to verify these specific pressure limits.

Sources

Utah Code § 72-7-404 (2024) — https://le.utah.gov/xcode/Title72/Chapter7/72-7-S404.html UDOT Motor Carrier Division Rule R909-2 (2024) — https://rules.utah.gov/publicat/code/r909/r909-002.htm Federal Highway Administration (FHWA) Bridge Formula Guide (2023) — https://ops.fhwa.dot.gov/freight/publications/brdg_frm_wghts/

Frequently asked

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

The maximum weight for a tandem axle in Utah is 34,000 pounds on the Interstate system, provided the axles are spaced between 40 and 96 inches apart.

How much does a Utah overweight permit cost?

A single-trip overweight permit costs $60 for loads up to 125,000 pounds, with an additional $0.06 per ton-mile for weight over 80,000 pounds.

Can I carry 129,000 pounds in Utah?

Yes, Utah allows gross vehicle weights up to 129,000 pounds on designated routes for vehicles that have a permit and meet the 9-axle bridge formula requirements.

What is the fine for being 5,000 pounds overweight in Utah?

According to Utah's graduated fine schedule, a 5,000-pound overweight violation typically results in a fine of approximately $100, though total costs can increase with court fees and surcharges.

Does Utah require a permit for 80,001 pounds?

Yes, any weight exceeding the federal 80,000-pound limit on the Interstate System requires either a single-trip or annual overweight permit from UDOT.