Missouri Oversize and Overweight Permitting Guide

In Missouri, you need an oversize permit whenever your vehicle or load exceeds the statutory dimensions defined by the Missouri Department of Transportation (MoDOT). Standard legal limits allow for a maximum width of 8 feet 6 inches, a maximum height of 13 feet 6 inches, and a gross vehicle weight of 80,000 pounds on the interstate system. Any load exceeding these measurements requires a single-trip or multi-trip permit to legally traverse state-maintained highways and interstates like I-70, I-44, and I-55. DispatchTool assists carriers in managing these compliance requirements by centralizing load documents and permit copies for easy driver access via mobile devices. The platform streamlines the coordination between dispatchers and drivers to ensure that specific route restrictions dictated by MoDOT are followed precisely. To start organizing your fleet’s compliance documentation, create a DispatchTool account.

Missouri Legal Width and Height Limits

The legal width limit for all vehicles in Missouri is 8 feet 6 inches (102 inches). This measurement includes the load but excludes safety devices such as mirrors or side marker lamps, provided they do not exceed the width by more than 10 inches on either side. The legal height limit is 13 feet 6 inches on all highways, though some specific routes may have lower clearance. If a load reaches 14 feet in height, MoDOT requires the carrier to perform a route survey to ensure clearance under bridges and utility lines. Loads exceeding 16 feet in width generally require a civilian escort and may be restricted to specific travel windows to prevent traffic congestion.

Length Restrictions for Combinations

Missouri statutes define length limits based on the vehicle configuration. A single motor vehicle is limited to 45 feet. For a tractor-semitrailer combination, there is no overall length limit on the primary interstate and designated highway system, provided the trailer does not exceed 53 feet. On non-designated supplemental routes, the overall length is capped at 60 feet unless a permit is obtained. Specialized equipment, such as auto transporters, are allowed up to 80 feet plus overhang (4 feet front, 3 feet rear) before requiring an oversize permit, per 304.170 RSMo.

Missouri Weight Limits and Axle Requirements

The maximum gross vehicle weight (GVW) without a permit is 80,000 pounds on the interstate system. Axle weight limits are strictly enforced: a single axle is limited to 20,000 pounds, and a tandem axle group (spaced 40 to 96 inches apart) is limited to 34,000 pounds. Missouri uses the Federal Bridge Formula to calculate allowable weights for various axle spacings. Overweight permits can be issued for non-divisible loads up to 160,000 pounds GVW, depending on the number of axles and the spacing between them. Loads exceeding 160,000 pounds are classified as superloads and require a detailed structural analysis by MoDOT engineers, which can take up to 5-10 business days for approval.

Permit Fees and Application Process

MoDOT issues several types of permits through the MoDOT Carrier Express system. A standard single-trip permit costs $15 for oversize and starts at $15 for overweight loads, increasing by $20 for every 10,000 pounds over the initial 80,000-pound limit. For frequent haulers, a multi-trip (annual) blanket permit is available for $128 for oversize loads not exceeding 12 feet 4 inches in width or 150,000 pounds in weight. Most permits are issued electronically and must be carried in the cab of the truck, either in paper form or as a digital copy on a mobile device, as verified during roadside inspections.

Escort Vehicle Requirements

Pilot cars or escorts are mandatory in Missouri when dimensions reach specific thresholds. One escort is required for loads over 12 feet 4 inches wide on two-lane highways or over 14 feet wide on divided highways. Two escorts (front and rear) are required for loads exceeding 14 feet in width on two-lane roads. If a load is over 15 feet 6 inches high, a front escort equipped with a high-clearance pole is mandatory. Escort drivers must have a valid driver's license and the vehicle must be equipped with a "Wide Load" or "Oversize Load" sign measuring at least 5 feet by 12 inches with 8-inch high letters.

Travel Time Restrictions and Holidays

Oversize loads in Missouri are generally permitted to travel from sunrise to sunset, seven days a week. However, loads exceeding 14 feet in width are restricted to Monday through Friday travel only. In major metropolitan areas like St. Louis and Kansas City, movement is prohibited during peak commuter hours (6:30 AM to 9:00 AM and 3:30 PM to 6:00 PM). Furthermore, permit travel is typically banned on major holidays, including New Year's Day, Memorial Day, Independence Day, Labor Day, Thanksgiving, and Christmas. If a holiday falls on a Sunday, the following Monday is also restricted.

Signage and Lighting for Oversize Loads

All permitted oversize loads must display "Oversize Load" signs on the front and rear of the vehicle. These signs must be at least 7 feet long and 18 inches high with black lettering on a yellow background. Additionally, red or orange fluorescent flags, at least 18 inches square, must be placed at the four corners of the load and at any wider extremities. For night travel (when specifically authorized for loads only slightly over-width), amber clearance lights and side marker lamps must be used to clearly define the perimeter of the trailer and the load.

Sources

Missouri Department of Transportation (MoDOT) Motor Carrier Services (2024) — https://www.modot.org/mcs Missouri Revised Statutes (RSMo) Chapter 304 (2024) — https://revisor.mo.gov/main/OneChapter.aspx?chapter=304

Frequently asked

What is the max height in Missouri without a permit?

The maximum legal height in Missouri is 13 feet 6 inches. Anything taller requires an oversize permit from MoDOT.

How much is an overweight permit in Missouri?

A single-trip overweight permit starts at $15 for the first 80,000 pounds and increases by $20 for every additional 10,000 pounds.

When are pilot cars required in Missouri?

Pilot cars are required if the load exceeds 12 feet 4 inches in width on two-lane roads or 14 feet in width on divided highways.

Can oversize loads travel on weekends in Missouri?

Yes, loads up to 14 feet wide can travel from sunrise to sunset on Saturdays and Sundays, unless it is a holiday weekend.

Is a permit required for 53-foot trailers in Missouri?

No, a 53-foot trailer does not require a permit on the designated primary highway system, provided the total length doesn't violate bridge laws.