Mississippi Truck Weight Limits and Regulations

Mississippi regulates commercial vehicle weights through the Mississippi Department of Transportation (MDOT) and the Mississippi Highway Safety Patrol. The state enforces a maximum gross vehicle weight (GVW) of 80,000 pounds on the interstate system and designated highways, consistent with federal standards. For state highways not designated as part of the primary system, the limit is often lower, frequently capped at 57,650 pounds or 73,280 pounds depending on the specific route and axle spacing. Motor carriers must adhere to the bridge formula to ensure weight is distributed across axles to prevent structural damage to the state's infrastructure. DispatchTool assists carriers in navigating these complex restrictions by providing truck-safe routing that accounts for Mississippi’s specific weight-restricted bridges and local road closures. By integrating live MDOT bridge data into the dispatch workflow, drivers can avoid routes where their current manifest exceeds legal limits, reducing the risk of overweight citations that often exceed $500 per violation. Create a DispatchTool account to automate route planning based on your specific equipment weight and axle configuration.

Standard Gross Vehicle Weight Limits

In accordance with Mississippi Code § 63-5-33, the maximum gross weight allowed on any combination of units is 80,000 pounds on the Interstate System and other designated highways. For vehicles operating on non-designated state highways, the gross weight is limited by the number of axles and the distance between them, often defaulting to a maximum of 73,280 pounds unless a permit is obtained. The state utilizes the Federal Bridge Formula B to calculate the maximum weight for any group of two or more consecutive axles. Specifically, the formula is W = 500 [LN/(N-1) + 12N + 36], where 'W' is the overall gross weight, 'L' is the distance in feet between the extremes of any group of two or more consecutive axles, and 'N' is the number of axles in the group.

Axle Weight Restrictions

Mississippi law dictates specific limits for individual axle groups to protect pavement integrity. On designated highways, single axles are limited to 20,000 pounds, while tandem axles (spaced more than 40 inches but no more than 96 inches apart) are limited to 34,000 pounds. For non-designated highways, these limits are reduced to 18,000 pounds for a single axle and 32,000 pounds for a tandem axle. Steering axles are generally limited to the lesser of 20,000 pounds or the manufacturer's rated capacity of the tires. MDOT enforcement officers utilize both fixed weigh stations and portable scales to verify these weights, focusing on the heavy transit corridors like I-10, I-20, and I-55.

Overweight Permit Requirements

When a load cannot be reasonably dismantled or divided, MDOT's Office of Enforcement issues oversize/overweight (OS/OW) permits. A single-trip permit for an overweight vehicle typically costs $10.00 plus an additional fee based on the weight exceeding 80,000 pounds, calculated at $0.05 per mile per 1,000 pounds of excess weight. For example, a vehicle weighing 90,000 pounds traveling 100 miles would incur a weight-based surcharge of $50.00 in addition to the base permit fee. Annual permits are available for specific commodities, such as sealed ocean containers or timber, with fees ranging from $500 to $1,500 depending on the commodity and requested weight threshold.

Agricultural and Timber Exemptions

Mississippi provides specific weight allowances for vehicles transporting raw agricultural products or unrefined forest products. Under Mississippi Code § 63-5-33, these vehicles may be allowed a 5% variance on gross weight and axle weight when traveling from the point of harvest to the first point of processing, provided they are not on the Interstate System. This effectively allows for a gross weight of up to 84,000 pounds on designated state highways. However, these vehicles must still comply with posted bridge limits, which are strictly enforced. Drivers must carry proof that the load originated within the state to qualify for these specific harvest-season tolerances.

Tire and Load Width Regulations

Weight limits are also constrained by tire width in Mississippi. The law prohibits weights exceeding 650 pounds per inch of tire width for most commercial vehicles. Additionally, while the standard width limit is 8 feet 6 inches (102 inches), any load exceeding this requires an oversize permit. Height is limited to 13 feet 6 inches without a permit. MDOT requires that any vehicle exceeding 10 feet in width must have 'Oversize Load' signs and, in many cases, escort vehicles depending on the specific highway's lane width and traffic volume. These safety measures ensure that heavy loads do not impede the flow of traffic or cause collisions on narrow rural routes.

Penalties for Overweight Violations

Fines for overweight violations in Mississippi are scaled based on the amount of excess weight. According to MDOT enforcement guidelines, the fine is calculated per pound of excess. For the first 1,000 pounds over the limit, the fine is typically $0.01 per pound. This rate increases significantly as the violation grows: 1,001 to 2,000 pounds over costs $0.02 per pound, and violations exceeding 5,000 pounds over the limit can cost $0.05 per pound or more. A truck that is 10,000 pounds overweight could face a fine of $500 plus court costs. Furthermore, the driver may be required to offload the excess weight on the spot before the vehicle is allowed to proceed, leading to significant delivery delays.

Sources

Mississippi Department of Transportation (MDOT) Enforcement (2024) — https://mdot.ms.gov/portal/enforcement Mississippi Code Title 63 - Motor Vehicles and Traffic Regulations (2023) — https://www.lexisnexis.com/hxt/mississippi/default.hxt Federal Highway Administration (FHWA) Bridge Formula Weights (2022) — https://ops.fhwa.dot.gov/freight/publications/brdg_frm_wgt/

Frequently asked

What is the maximum gross weight on Mississippi interstates?

The maximum gross vehicle weight on Mississippi interstates is 80,000 pounds, provided the vehicle meets the Federal Bridge Formula requirements for axle spacing.

How much does a single-trip overweight permit cost in MS?

A single-trip permit starts at a base fee of $10.00, with an additional mileage-based fee of $0.05 per mile for every 1,000 pounds over the standard 80,000-pound limit.

Are there weight tolerances for hauling logs in Mississippi?

Yes, timber and agricultural haulers are granted a 5% tolerance on non-interstate state highways, allowing for a maximum gross weight of approximately 84,000 pounds.

What are the tandem axle weight limits in Mississippi?

On designated highways and interstates, the tandem axle limit is 34,000 pounds. On non-designated state roads, this limit drops to 32,000 pounds.

Where can I purchase Mississippi trip and fuel permits?

Permits can be purchased online through the MDOT Alabama-Mississippi-South Carolina-Georgia (SAM) regional permit system or at MDOT district offices and authorized permit services.