Tennessee Oversize Load Permits, Regulations & Axle Rules

Standard overdimensional loads in Tennessee run on a daylight-only schedule, defined as 30 minutes before sunrise to 30 minutes after sunset, Monday through Saturday. Sunday movement is prohibited for any load that is oversize, whether over width, height, or length. Overweight-only loads get more flexibility: a weight-only permit authorizes 24-hour continuous movement, seven days a week including Sunday. For most mixed OS/OW moves, the operative rule is daylight, Monday through Saturday.

Seven holidays close the road entirely: New Year's Day (January 1), Good Friday, Memorial Day (last Monday in May), Independence Day (July 4), Labor Day (first Monday in September), Thanksgiving Day, and Christmas Day (December 25). No permitted movement issues for those days.

Tennessee also runs a pair of named rush-hour curfews. For loads equal to or longer than 85 feet, or wider than 12'6", no travel is allowed within any city limits or heavily traveled adjoining commercial or residential area on weekdays between 7:00 AM and 9:00 AM and again between 4:00 PM and 6:00 PM. The second curfew is more geographic: on Interstate highways within Davidson (Nashville), Rutherford, Hamilton (Chattanooga), Knox (Knoxville), and Shelby (Memphis) counties, no OS/OW movement that requires any escort at all may occur during those same Monday-through-Friday windows regardless of permit type. These two curfews function independently: a load running on a county two-lane outside a city is covered by the first rule, and a load on I-40 through Nashville hits the second.

Weather halts movement when conditions would make the move unsafe. Tennessee publishes no specific visibility or wind-speed thresholds; the standard is whether conditions are hazardous. No continuous 24-hour travel applies to combined oversize/overweight loads, houseboats, or Super Loads.

Tennessee provides distinct treatment to several commodity categories, and the differences are sometimes large enough to reshape the permit and escort structure.

Houseboats travel under progressively tighter windows as width increases. At 14' to 16' wide, movement is limited to Monday through Friday 9:00 AM to 4:00 PM and Saturday sunrise to sunset, with no annual permits available. From 16' to 17' wide, travel narrows to Tuesday, Wednesday, and Thursday only, 9:00 AM to 4:00 PM. The widest houseboats (17' to 18') require three escort vehicles, two in front and one rear, and are also confined to Tuesday, Wednesday, and Thursday, 9:00 AM to 4:00 PM. Nothing over 18 feet wide may be transported. Houseboats cannot travel on any holiday.

Sealed containerized (ocean-going) cargo qualifies for nondivisible-load treatment on international trade moves supported by an international bill of lading. The trade-off is strict axle and weight limits: five axles minimum, 20,000 lbs per axle maximum, and a 90,000 lbs GVW cap. These moves are legal-dimensional (no oversize) but authorized for 24-hour continuous movement, Monday through Sunday.

Poles, logs, and timber in single-length pieces are exempt from Tennessee's general length limits, provided the overall vehicle-and-load combination does not exceed 75 feet. Above 75 feet a standard overlength permit is required. Farm equipment used exclusively for normal farm purposes is exempt from permit requirements entirely. Seed cotton module vehicles may obtain a special one-year permit allowing a trailer width up to 108 inches, versus the standard 102-inch limit. Stinger-steered automobile transporters may run up to 80 feet overall with front overhang under 4 feet and rear overhang under 6 feet.

Tennessee's semitrailer length rule deserves a flag for carriers reading a 53-foot trailer as automatically legal: the state measures from the kingpin to the rearmost point of the towed vehicle including any projecting load, with a 52-foot maximum. A rear overhang that pushes the kingpin-to-rear measurement past 52 feet requires an overlength permit.

Tennessee's top-tier permit category is called a Super Load (the rules also use the phrase "superheavy and/or extra overdimensional"). A load enters this tier when it exceeds any one of three thresholds: gross weight over 165,000 lbs, width over 16 feet, or height over 15'6". Length is not a superload trigger in Tennessee; there's no combined-length figure that by itself pushes a load into Super Load status.

Loads that fall within the auto-issue window (up to 16' wide, up to 15'6" high, and up to 165,000 lbs) process in three to ten business days depending on whether they involve only overdimensions or also carry excess weight. A Super Load, by definition, sits outside that window and gets manual review. The Department may issue or withhold the permit at its sole discretion based on engineering judgment, necessity, safety, and the feasibility of alternative transport modes. Carriers who hear "sole discretion" should take it literally; documentation quality and route preparation matter significantly here.

The written application must go to the Supervisor of Overweight and Overdimensional Permits and must include a complete and detailed description of the movement, a detailed sketch of the vehicle and load, tire sizes and contact pressures, axle spacings, per-axle load distribution, overall dimensions, and a traffic control proposal. Depending on what pushes the load into Super Load territory, additional requirements follow: a move over 16 feet wide requires a letter of necessity or shipper's letter demonstrating the move is essential to public health, welfare, safety, or defense. A load over 15 feet high requires a route survey (see Route Survey section). A move over 150,000 lbs requires Structures Division approval before the permit can issue; the Department performs a bridge evaluation on the proposed route, and the applicant pays the estimated cost in advance: $100 for moves up to 250,000 lbs, $300 from 250,001 to 500,000 lbs, and actual cost above 500,000 lbs. Engineering examinations may also be required at the applicant's expense for any Super Load regardless of trigger type.

There's no codified lead-time requirement stated in the rules for Super Loads in general, but loads requiring Tennessee Highway Patrol escorts, common for Super Loads that hit 18-foot width or height thresholds, carry a minimum 10-day processing requirement that effectively sets the floor for those moves.

Tennessee requires a route survey whenever a load exceeds 15 feet in height. The survey is carrier-performed rather than state-performed: the permittee must determine all vertical clearances along the proposed route by running a front escort vehicle ahead of the load equipped with physical protrusions equal to the full height of the permitted vehicle. That escort must be able to immediately notify the driver by radio if any structure ahead has a clearance less than the load's height, and the permitted vehicle must follow at sufficient distance to stop on that warning. The route survey obligation attaches to the permit, not just the first trip: if Tennessee Highway Patrol escort is involved, the route survey on file is voided 30 calendar days after THP receives the documentation, and a fresh survey is required before a subsequent movement.

For loads over 16 feet wide, a letter of necessity or shipper's letter stands in as the required justification document rather than a traditional route inspection, though engineering examinations on width clearances may also be required at the Department's discretion.

Weight-based review follows a parallel track. Any move over 150,000 lbs gross requires Structures Division approval before the permit issues. This is a bridge engineering evaluation conducted or directed by TDOT (the applicant doesn't perform it), and the applicant funds estimated costs up front. This structural review effectively must be completed before the permit can issue, making it a precondition of movement just as the height-triggered route survey is.

TDOT publishes a Route Survey/Traffic Control Plan form on its resources page, and TDOT also publishes a monthly-updated list of overpasses with vertical clearances under 14'6" to assist carriers in route planning.

Tennessee Highway Patrol (THP) is the law-enforcement escort agency for OS/OW moves in Tennessee. Two codified dimensional thresholds require THP: a load 18 feet or wider traveling on an Interstate or federal-aid highway, and a load 18 feet or taller traveling on any highway. A third basis, complexity of the load or route, is discretionary; TDOT's Permit Office evaluates THP need based on load dimensions, movement complexity, travel speed, and route conditions, and may require THP even when the dimensional thresholds aren't met.

THP escort is in addition to, not a replacement for, civilian pilot cars. A move at 18' wide or 18' high still needs whatever civilian escorts its width, height, or length dimensions require under the standard escort tables, and THP layers on top of that. The Permit Office coordinates THP; carriers don't contact THP directly to book escorts. THP requires a minimum of 10 business days' advance notice before the escort date, and the move can't proceed until THP has confirmed availability and the permit has issued. Before the escort begins, THP conducts at least a Level 2 North American Standard inspection of the vehicle and load. Minimum staffing for a THP escort is two to three troopers. The estimated cost is approximately $60 per hour, and the permittee reimburses TDOT for the actual cost of the law-enforcement escort; billing is quarterly and available 90 days after the move.

For loads below the 18-foot width and height thresholds, civilian escort vehicles handle the codified requirements. Escort thresholds by dimension: width over 12'6" to 14', one rear escort on Interstate and four-lane highways, one front on two-lane; width over 14' to 16', front and rear on all roads; height over 15', one front escort with height protrusions; overall length over 85' to 120', one rear escort; overall length over 120', front and rear. Loads between 75' and 85' long require no escort but must carry an amber rotating or strobe light on the rear sign, visible from 500 feet in all directions.

Civilian escorts must be in vehicles weighing over 2,000 lbs with a manufacturer's GVWR under 10,000 lbs. Escort vehicles must carry OVERSIZE LOAD signs, an amber rotating or strobe light visible 500 feet at 360 degrees, two red or fluorescent orange flags at least 18 inches square on a roof rack, two-way radio communications, two 5-pound fire extinguishers, a stop-and-go paddle, and a safety vest.