When an oversize permit is required in Kentucky

Dec. 12, 2025, 6:22 p.m.
Kentucky requires an Oversize Permit anytime a commercial vehicle or load exceeds the legal size limits established by the Kentucky Transportation Cabinet (KYTC). These limits apply to trucks, trailers, combinations, and both divisible and non-divisible loads. Below is the full breakdown.
Oversize Permit in Kentucky

1. Legal Size Limits in Kentucky

You must obtain an oversize permit if your vehicle or load exceeds any of the following:

A. Width Limit

  • Legal width: 8 ft 6 in (102")

A permit is required for:

  • Any load or vehicle over 8’6” wide

  • Includes machinery, equipment, buildings, large tanks, etc.

Safety devices and mirrors may extend slightly beyond 102" without needing a permit.

B. Height Limit

  • Legal height: 13 ft 6 in

A permit is required for:

  • Any load or vehicle taller than 13’6”

Kentucky has many low bridges, so height routing is critical.

C. Length Limits

Length varies by vehicle type:

Single Vehicle

  • Legal length: 45 ft

Semi-trailer combinations

  • Tractor–semitrailer (standard routes): 53 ft trailer

  • Overall length is usually unrestricted on designated highways, but restricted elsewhere.

A permit is required if:

  • Trailer exceeds 53 ft on non-designated roads

  • The total combination exceeds 65 ft on restricted routes

  • Special equipment or oversized machinery causes overlength

D. Overhang Limits

  • Front overhang: 3 ft

  • Rear overhang: 4 ft

Any overhang beyond these limits → oversize permit required.

2. Oversize Permits for Non-Divisible Loads

You must obtain an oversize permit if the non-divisible load exceeds legal dimensions.

Non-divisible examples:

  • Construction machinery

  • Cranes, excavators, bulldozers

  • Industrial tanks

  • Bridge beams

  • Wind turbine components

  • Prefabricated buildings

If it cannot be reduced without damage → it qualifies for oversize permitting.

3. Divisible Load Rules in Kentucky

Divisible loads cannot be oversize.
(Example: pallets, grain, lumber, pipe bundles, coils.)

If a divisible load exceeds legal dimensions, it must be reduced, not permitted.

Only weight can be permitted with certain divisible commodities (coal, logs, aggregates, etc.), but size cannot.

4. When Special or Superload Permits Are Required

A standard oversize permit is not enough if the load exceeds certain thresholds.

Superload thresholds in Kentucky:

You need special engineering review if the load is:

  • Over 16 ft wide

  • Over 15 ft high

  • Over 120 ft long

  • Or exceeds high weight thresholds (combined OS/OW criteria)

These moves require KYTC bridge review and custom routing.

5. Escort/Pilot Car Requirements That Trigger a Permit

Even if you are just barely above legal size, you still must have a permit when escort rules apply:

  • Width greater than 12 ft requires escorts

  • Height over 14 ft 6 in often requires pole car + permits

  • Length over 75–90 ft requires escorts depending on the route

If an escort is required → a Kentucky oversize permit is mandatory.

6. Short-Distance and Local Moves

Even for small or local trips, a permit is still required if:

  • Equipment is crossing a public highway

  • Dimensions exceed legal limits

  • The move is between job sites or farms

Construction and agricultural equipment still requires oversize permits unless an exemption applies to weight only.

7. Summary — When You MUST Have an Oversize Permit in Kentucky

You need an oversize permit in Kentucky if any of the following apply:

  • Width exceeds 8’6”

  • Height exceeds 13’6”

  • Length exceeds allowed trailer or combination dimensions

  • Overhang exceeds 3 ft front or 4 ft rear

  • Load is non-divisible and above legal dimensions

  • Escort or pilot car is required

  • Superload thresholds are exceeded

  • Even short or local moves cross public roads while oversized

If any legal dimension is exceeded → Kentucky oversize permit required.

 

https://drive.ky.gov/Motor-Carriers/Overweight-Over-Dimensional/Pages/default.aspx