Oversize overweight (OS OW) permit rules in Kentucky

1. Governing law & regulations

The primary regulation is 601 KAR 1:018 – Special overweight or overdimensional motor vehicle load permits (Kentucky Administrative Regulations) which implements statute under KRS 189.270, KRS 189.271, KRS 189.2715, KRS 189.2717.
Additional regulation for farm equipment: 601 KAR 1:019 – Overweight or overdimensional farm equipment.
General weight limits before requiring permits are under 603 KAR 5:066 – Weight (mass) limits for trucks.

A permit is required prior to movement of any vehicle/load exceeding the legal statutory or regulatory limits for width, height, length or weight.
Specifically:
- Width: Loads wider than 8 ½ feet (8'6") generally require a permit.
- Height: Loads taller than 13 feet 6 inches trigger a permit requirement.
- Weight/axle limits: If gross weight or axle group weights exceed the statutory/regulatory limits, a permit is needed.
Load divisibility: A permit typically will not be issued for a divisible load that could be dismantled, divided, or rearranged to meet legal limits.
Farm equipment exception: Some farm equipment is exempt (moving between farms, from farm to dealer, etc.) under 601 KAR 1:019, but still subject to safety/escort requirements.

Width: Legal width is 8 ft 6 inches (8'6") on interstates/designated highways. Loads wider than that require a permit.
Height: Standard maximum height is 13 ft 6 in. Loads exceeding that height must obtain a permit, and loads above 15 ft 6 in may need a route survey.
Length: There are length limits; for example a manufactured home with combined length of towing vehicle + home greater than 120 ft is prohibited.

Steering axle: max ~20,000 lbs.
Single dual-wheel axle: ~24,000 lbs.
Tandem dual-wheel axle group (5 axle combination): ~45,000 lbs.
Tandem dual-wheel axle group (6+ axle combination): ~48,000 lbs.
Tridem dual-wheel: ~60,000 lbs.
Gross weights by configuration:
- 5-axle combination: up to ~96,000 lbs.
- 6-axle: up to ~120,000 lbs.
- 7-axle: up to ~160,000 lbs (for certain permits).
The formula also provides that axle weight cannot exceed “700 lbs × tire width (in inches)” or the specified maxima.

Single trip permit: Valid for one move. Under 601 KAR 1:018, the single-trip permit is valid for one move and duration of up to 10 days.
Annual permit: Valid for unlimited moves (within conditions) for 365 days.
Application:
- Complete form TC 95-10 (Worksheet for single-trip) or TC 95-25 (Application for annual) and submit to Division of Motor Carriers.
- Payment of applicable fees: e.g., single-trip permit fee and annual permit fee are specified under statute/regs.
- Provide required information: vehicle and towing unit details (VIN, license plate, jurisdiction), description of cargo, route, registration details, axle configuration, etc.
Online system: www.kentuckytruckingonline.com

Permits specify the approved route. Any deviation from the route must receive prior written approval from the Division of Motor Carriers.
Travel hours: Generally allowed 24/7 unless the permit says otherwise. However, specific loads such as mobile homes may have daylight-only restrictions.
County/peak-traffic restrictions: In certain counties (e.g., Boone, Campbell, Fayette, Jefferson, Kenton) permitted loads are restricted from traveling in rush-hour windows (7 am-9 am, 4 pm-6 pm) on weekdays.
Weather/conditions: Loads wider than 12 ft cannot move if a wind advisory is issued or if road conditions are dangerous.
Highway/truck network constraints: A permit may be denied or restricted if the route includes interstate segments and the load is divisible, or if bridges/structures on the route cannot support the load.

Oversize loads may require one or more escort vehicles (pilot cars) depending on width, height, route, and local/permit conditions.
The permit holder is responsible for the safe movement of the load, including any necessary traffic control when crossing bridges or where the load encroaches on other lanes.
The permit holder is financially responsible for any damage to roads, signs, guardrails, other public/private property caused by the load movement.

Kentucky will not issue an OS/OW permit for a load that is reasonably divisible — i.e., could be reconfigured, disassembled or divided to meet legal limits — except under specific statutory authority.
Loads considered “non-divisible” (such as large equipment or structures where dismantling isn’t feasible) may qualify for permit if other conditions met.

Always submit your permit application early to allow time for review (especially annual/special loads).
Review the approved route carefully and ensure trucks follow exactly — deviation without approval can invalidate the permit or lead to enforcement.
Carry the physical or electronic permit in the vehicle at all times and produce it when requested by law enforcement.
Check for local county/truck-traffic restrictions, rush-hour windows, weather advisories (especially for wide loads).
Ensure tractor/trailer equipment is adequate (braking, horsepower, registration weight) for the load. Under KY rules, gross/axle overweight not permitted on units less than 5 axles.
Confirm route clearances (bridges, underpasses) if height or width is significant. For heights over 15’6” a route survey may be required.
Monitor special load categories (manufactured homes, seaworthy containers, etc) which may have additional requirements.
Keep documentation showing load is non-divisible if required.
Remember: The permit does not guarantee safe passage — you are responsible for compliance and safety.