Wisconsin Commercial Vehicle Weight Limits and Regulations

Wisconsin enforces strict commercial vehicle weight limits governed by Chapter 348 of the Wisconsin Statutes. The standard maximum gross vehicle weight for trucks operating on the State Trunk Highway System is 80,000 pounds, provided the vehicle meets the requirements of the Federal Bridge Formula B. These limits ensure the structural integrity of the state's 11,500 miles of highway and over 14,000 bridges. Carriers must adhere to specific axle weight restrictions: 20,000 pounds for a single axle and 34,000 pounds for a tandem axle, with a maximum steering axle weight typically capped at 13,000 pounds depending on tire width. Navigating these limits is critical for compliance and safety, especially when transitioning between Interstates and local town roads which may have seasonal postings. DispatchTool helps carriers manage these complexities by providing truck-safe routing that accounts for vehicle weight profiles and state-specific road restrictions. By integrating weight data into the dispatch workflow, operators can avoid costly overweight citations and infrastructure damage. Create a DispatchTool account to start planning routes that automatically respect Wisconsin's legal weight thresholds and bridge laws.

Standard Weight and Axle Configurations

Under Wis. Stat. § 348.15, the maximum weight for any single axle is 20,000 pounds, while a tandem axle—defined as two axles spaced more than 40 inches but not more than 96 inches apart—is limited to 34,000 pounds. For a standard 5-axle tractor-trailer combination, the gross vehicle weight (GVW) cannot exceed 80,000 pounds without a permit. The weight on any group of two or more consecutive axles is determined by 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. This calculation prevents excessive stress on bridge spans across the state.

Seasonal Weight Restrictions (Spring Thaw)

Wisconsin implements seasonal weight restrictions, often referred to as 'frost laws,' to protect roads during the spring thaw. The Wisconsin Department of Transportation (WisDOT) typically begins these restrictions in early March, dividing the state into zones: Zone 1 (Southern), Zone 2 (Central), and Zone 3 (Northern). During this period, Class B highways are restricted to 60% of their normal legal weight. For example, a vehicle normally allowed 20,000 pounds on a single axle is limited to 12,000 pounds. Local municipalities may also post specific weight limits on town roads, which can be as low as 6 tons GVW.

Oversize and Overweight (OSOW) Permitting

If a load is non-divisible and exceeds 80,000 pounds, a permit from the WisDOT Bureau of Highway Maintenance is required. Single-trip permits typically cost $70 for weights up to 150,000 pounds, plus additional mileage fees if the weight exceeds that threshold. Multiple-trip (annual) permits are available for specific commodities, such as raw forest products or sealed intermodal containers. An annual permit for a vehicle up to 90,000 pounds generally costs $200. Carriers must provide specific axle spacings and weights during the application process to ensure the proposed route can handle the load.

Tire Loading and Pressure Limits

Wisconsin regulations also specify weight limits based on tire width to prevent pavement rutting. According to Wis. Stat. § 348.15(3), the weight on a tire cannot exceed 800 pounds per inch of tire width. For a standard 11-inch wide tire, the maximum load would be 8,800 pounds, though this is usually superseded by the axle limit of 20,000 pounds for single axles. However, for specialized heavy-haul equipment, this tire-to-pavement ratio is strictly scrutinized during the permitting process. Inspectors use portable or fixed scales to verify that these ratios are maintained at all times.

Exemptions for Agricultural and Forest Products

Specific exemptions exist for the transportation of agricultural products and raw forest products. Under Wis. Stat. § 348.15(3)(br), vehicles transporting peeled or unpeeled forest products cut crosswise or salt for highway winter maintenance are allowed a gross weight of 90,000 pounds on a vehicle with five or more axles, provided the distance between the first and last axle is at least 37 feet. During the annual 'harvest emergency' declared by the Governor, certain agricultural commodities may exceed standard weight limits by up to 15% to facilitate efficient crop movement.

Bridge Formula Application in Wisconsin

Wisconsin uses the Federal Bridge Formula B to protect the state's 14,000+ bridges. This formula determines the maximum weight any set of axles may carry based on the distance between them. For instance, a tri-axle group with a 9-foot spread is generally limited to 42,500 pounds rather than the 54,000 pounds that three single axles would theoretically be allowed. Failure to comply with bridge formula limits can result in fines exceeding $1,000, especially if the violation occurs on a weight-restricted bridge marked with specific R12-1 or R12-5 signage.

Sources

Wisconsin Department of Transportation (WisDOT) (2024) — https://wisconsindot.gov/Pages/dmv/com-drv-vehs/mtr-car-trkr/size-wt.aspx Wisconsin State Legislature Chapter 348 (2023) — https://docs.legis.wisconsin.gov/statutes/statutes/348 Federal Highway Administration (FHWA) Bridge Formula Guide (2022) — https://ops.fhwa.dot.gov/freight/publications/brdg_frm_wghts/

Frequently asked

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

The maximum legal weight for a tandem axle on Wisconsin highways is 34,000 pounds, provided the axles are spaced between 40 and 96 inches apart.

How much does an overweight permit cost in Wisconsin?

A single-trip overweight permit for non-divisible loads up to 150,000 pounds costs $70. Annual permits for weights up to 90,000 pounds typically cost $200.

When do spring weight restrictions typically start in Wisconsin?

Spring thaw restrictions usually begin in early March, depending on weather conditions, and stay in effect for approximately 6 to 8 weeks to protect vulnerable road beds.

Are there weight tolerances for livestock haulers in Wisconsin?

Wisconsin does not provide a general weight tolerance for livestock; however, haulers must comply with the 80,000-pound GVW limit unless a specific emergency exemption is active.

What is the fine for an overweight truck in Wisconsin?

Fines are calculated based on the number of pounds over the limit. A violation of 5,000 pounds over can result in a fine of roughly $500 to $700, plus court costs and surcharges.