Mississippi Oversize and Overweight Permitting Guide

In Mississippi, you need an oversize permit whenever your vehicle or load exceeds the legal dimensions of 8 feet 6 inches in width, 13 feet 6 inches in height, or a total length of 53 feet for a semi-trailer. Weight limits also trigger permitting requirements when the gross vehicle weight (GVW) surpasses 80,000 pounds or when individual axle weights exceed the maximum allowances set by the Mississippi Department of Transportation (MDOT). Carriers must obtain these permits before entering the state or moving the load on state-maintained highways. Failure to secure a permit can result in significant fines, being placed out-of-service by the Mississippi Department of Public Safety, and potential liability for infrastructure damage. DispatchTool assists carriers by providing truck-safe routing that accounts for these specific Mississippi dimension restrictions and allows dispatchers to attach digital permit copies directly to the driver's trip folder. Create a DispatchTool account to manage your oversized load documentation and route planning in one interface.

Mississippi Legal Width and Height Limits

The maximum legal width for any vehicle on Mississippi highways is 8 feet 6 inches. Any load wider than this requires an oversize permit. Height is strictly capped at 13 feet 6 inches for standard travel. If a load exceeds 13 feet 6 inches, the carrier must perform a route survey to ensure clearance under bridges and utility lines, as the state has numerous older overpasses with clearances under 14 feet. It is the operator's responsibility to verify that the specific route can accommodate the excessive height, especially when traveling on non-interstate routes like US-49 or US-82.

Maximum Legal Length Requirements

Mississippi allows a maximum trailer length of 53 feet for a semi-trailer operated in a truck tractor-semitrailer combination. The overall length of the combination is not restricted on the state's designated truck network, provided the trailer stays within the 53-foot limit. However, for specialized combinations or loads where the trailer exceeds 53 feet, a permit is mandatory. For auto-transporters, the state allows a 65-foot length for traditional units and up to 80 feet for stinger-steered units, including a 3-foot front overhang and a 4-foot rear overhang without a permit.

Gross Vehicle Weight and Axle Limits

The standard legal gross vehicle weight (GVW) in Mississippi is 80,000 pounds. Individual axle weight limits are 20,000 pounds for a single axle and 34,000 pounds for a tandem axle group. If your load exceeds these weights, you must apply for an overweight permit. Mississippi MDOT evaluates overweight requests based on the number of axles and the spacing between them, often referred to as the bridge formula. Loads exceeding 150,000 pounds are classified as 'Superloads' and require a more intensive engineering review process which can take several business days to complete.

Escort Vehicle Requirements

Escort vehicles, or pilot cars, are required in Mississippi when loads exceed specific dimensions to ensure public safety. A single front escort is typically required for loads over 12 feet wide. If a load exceeds 15 feet in width, the state usually mandates both a front and a rear escort. For height, a pole car is required if the load exceeds 14 feet 6 inches. These escort vehicles must be equipped with amber flashing lights and 'Oversize Load' signs that are at least 5 feet wide and 12 inches high, with black lettering on a yellow background.

Travel Time Restrictions and Holidays

Mississippi generally permits the movement of oversize loads from 30 minutes before sunrise to 30 minutes after sunset, Monday through Saturday. Movement on Sundays is prohibited for most oversize loads unless specifically authorized by the MDOT Permit Office. Furthermore, oversize travel is restricted on major holidays including New Year's Day, Memorial Day, Independence Day, Labor Day, Thanksgiving Day, and Christmas Day. In heavy traffic areas like Jackson, Gulfport, and Southaven, MDOT may impose additional 'curfew' hours during morning and evening rush periods (typically 7:00 AM–9:00 AM and 4:00 PM–6:00 PM).

Permit Fees and Application Process

The cost of a single-trip oversize permit in Mississippi starts at a base rate of $10.00 for dimensions only. Overweight permits involve a more complex calculation, often costing $0.05 per ton-mile for the excess weight, with a minimum fee applied. Blanket (annual) permits are available for specific types of loads, such as heavy equipment or sealed containers, ranging from $100.00 to over $500.00 depending on the commodity and weight range. Applications are submitted through the Mississippi DOT's online permit system, which requires a valid USDOT number and proof of insurance.

Safety Equipment and Signage

All oversized loads must display 'Oversize Load' signs on the front of the tractor and the rear of the load or trailer. The signs must be 7 feet wide and 18 inches high with 10-inch black letters on a yellow background. Additionally, red or orange fluorescent flags, at least 18 inches square, must be placed at the widest extremities of the load. If the load is permitted for night travel (rare and case-specific), it must have amber lights on the front and sides and red lights on the rear to clearly define the perimeter of the vehicle.

Sources

Mississippi Department of Transportation (MDOT) Permit Manual (2024) — https://mdot.ms.gov/portal/enforcement_permits Mississippi Code Title 63 Chapter 5 (2023) — https://www.sos.ms.gov/admin-rules FMCSA State Weight Limits (2024) — https://ops.fhwa.dot.gov/freight/sw/brdgcalc/index.htm

Frequently asked

What is the maximum width allowed without a permit in Mississippi?

The maximum legal width allowed without a permit is 8 feet 6 inches. Anything exceeding this measurement requires a single-trip or annual oversize permit from MDOT.

Do I need an escort for a 12-foot wide load in Mississippi?

Yes, Mississippi typically requires one front escort vehicle for loads that exceed 12 feet in width on two-lane highways, though requirements may vary for multi-lane divided highways.

What is the maximum legal weight for a tandem axle in MS?

The maximum legal weight for a tandem axle group is 34,000 pounds. Any weight above this requires an overweight permit and adherence to the federal bridge formula.

Can I move an oversize load on Sunday in Mississippi?

Generally, no. Mississippi prohibits the movement of oversize loads on Sundays and major public holidays to reduce traffic congestion and improve safety.

How long is a single-trip oversize permit valid for?

A single-trip permit in Mississippi is typically valid for three to five days, depending on the route length and specific load conditions granted by the permit office.