Legal Dimensions



  • Motor-Trucks, 45-FT

  • Semitrailers, 53-FT, when operated in a Single Semitrailer combination. (Allows any size tractor)

  • Dual Trailers, 28-FT, if operated in a Tractor-Semitrailer-Trailer combination or a Tractor-Semitrailer-Semitrailer combination, not to exceed two towed units.

  • Overhang, 48-FT trailers may have up to 5-FT rear overhang on designated highways without obtaining an over-dimensional permit.


  • 8-FT and 06-IN


  • 13-FT and 06-IN

  • (Car Haulers 14-FT and 00-IN)


  • Twenty thousand (20,000) pounds per single axle, with axles less than forty-two (42) inches apart to be considered a single axle.

  • Thirty-four thousand (34,000) pounds on two (2) axles in a tandem arrangement which are spaced forty-two (42) inches or more apart and less than ninety-six (96) inches apart.

  • Forty-eight thousand (48,000) pounds on three (3) axles which are spaced forty-two (42) inches or more apart and less than one hundred twenty (120) inches apart.

  • No single axle in any arrangement shall exceed twenty thousand (20,000) pounds or seven hundred (700) pounds per inch of the aggregate width of all the tires on a single axle, whichever is less.

  • The total gross weight of the vehicle and load shall not exceed eighty thousand (80,000) pounds.

 In compliance with the Surface Transportation Assistance Act of 1982 (STAA) and DOT Appropriations Act of 1983 and KRS 189.222, Kentucky has established a network of highways on motor vehicles with increased dimensions (STAA vehicles) may operate. 23 CFR 658.19 requires each state to allow the increased dimension vehicles to operate within one (1) driving mile (1.61 kilometers) of the designated highways. On state-maintained highways in Kentucky, the increased dimension vehicles are allowed to operate within five (5) driving miles (8.05 kilometers) of a designated highway unless the designated highway is an interstate or a parkway, in which instance the increased dimension vehicles are allowed to operate within fifteen (15) miles (24.14 kilometers) of the interstate or parkway exit. The bus dimension limits are established in 603 KAR 5:071​.



  • A Single Unit Motor Vehicle, 45-FT

  • A Motor Vehicle and Trailer or Semitrailer combination, 65-FT

  • 8-FT

  • 13-FT and 06-IN


  • Class [A] Highways, 44,000 pounds

  • Class [AA] Highways, 62,000 pounds

  • Class [AAA] Highways, 80,000 pounds

If a truck tractor or semitrailer unit is exclusively engaged in the transportation of motor vehicles or boats, a three (3) foot (0.915 meters) front and four (4) foot (1.22 meters) rear overhang shall not be included in the measurement of the sixty-five (65) feet (19.812 meters) limit established in 603 KAR 5:070 – 3 (B).
23 CFR 658.19 requires that vehicles with increased dimensions transporting household goods and truck tractors towing only one (1) semitrailer not exceeding twenty-eight (28) feet (8.53 meters) in length be provided statewide access unless a route is excluded explicitly for safety reasons.


Gross or axle overweight shall not be permitted on a combination unit of less than five (5) axles; or on a single unit except on off-road equipment such as a road grader, mobile crane, or other self-propelled units. A vehicle shall not be issued an overweight permit that does not have a declared gross weight of at least 80,000 lbs. Maximum weights shall not be permitted unless all bridges and roads on the moving route have sufficient capacity to accommodate the load. The weight on a single axle in any combination shall not exceed the product of 700 pounds times the aggregate width in inches established by the manufacturer's stamped tire measurement of all the tires on the axle or the following axle or axle group weights, whichever is less.

Maximum Axle Weights

  • Steering axle - 20,000 pounds

  • Single Dual Wheel axle - 24,000 pounds

  • Tandem dual-wheel axle group if the combination vehicle has only five (5) axles total - 45,000 pounds

  • Tandem dual-wheel axle group if the combination vehicle has six (6) or more axles total - 48,000 pounds

  • Tridem dual-wheel axle group - 60,000 pounds

  • Trunnion axle 48,000 pounds

Combination Truck/Semitrailer

Per 601 KAR 1:018, combinations units of five (5), six (6), and seven (7) axle configurations shall be limited to the following:

  • Five (5) axle combination units may not exceed 96,000 pounds gross weight

  • Six (6) axle combination units may not exceed 120,000 pounds gross weight

  • Seven (7) axle combination units may not exceed 160,000 pounds gross weight

Self-Propelled Vehicles

  • Single axle: 23,000 pounds

  • Tandem dual-wheel axle group: 46,000 pounds

  • Tridem dual-wheel axle group: 69,000 pounds