Size and Weight Limitations

Vehicle size and weight limits on state and interstate highways are established by the state and federal governments. In Colorado, the Colorado Department of Transportation (CDOT) is responsible for regulating the movement of oversize and overweight vehicles on the state's highways. CDOT accomplishes this by issuing permits and providing route guidelines for commercial vehicles that exceed the normal size and weight limits allowed by law. The table below outlines state and federal limitations for vehicle size and weight.

Federal and State Motor Vehicle Size and Weight Limits

	Federal Regulations	State Law
Overall Vehicle Length	No federal length limit is imposed on most truck tractor‑semitrailers operating on the National Highway System (NHS). However, on the NHS, combination vehicles designed and used specifically to carry automobiles or boats in specially designed racks may not exceed a maximum overall vehicle length of 65 feet, or 75 feet, depending on the type of connection between the tractor and trailer.	45‑foot maximum overall single vehicle length 70‑foot combination length on all roads
Trailer Length	Federal law provides that no state can impose a length limitation of less than 48 feet (or longer if provided for by grandfather rights) on a semitrailer operating in any truck tractor‑semitrailer combination on the NHS. A state may permit longer trailers to operate on its national network highway. Similarly, federal law provides that no state can impose a length limitation of less than 28 feet on a semitrailer or trailer operating in a truck tractor‑semitrailer‑trailer combination on the NHS.	57.3 foot semitrailer on state, supplemental, and NHS highways 28.5 foot trailer length on state, supplemental, and NHS highways
Vehicle Width	On the NHS, states are restricted to vehicle width limitations of 8.5 feet.	8.5 feet
Vehicle Height	No federal vehicle height limit is imposed.	14.5 feet on NHS highways; CDOT designates highways with overhead structures that have a clearance of less than 14.5 feet
Single Vehicle Weight w/2 Axles	36,000 pounds	36,000 pounds NHS highways; 40,000 pounds state highways
Single Vehicle Weight w/3 or More Axles	54,000 pounds	54,000 pounds
Truck/Trailer or Combination of Vehicles	80,000 pounds	85,000 pounds

Source: Sections 42‑4‑502 through 42‑4‑509, C.R.S.

Vehicle weight. A commercial vehicle's gross combined weight rating (GCWR) is the maximum permissible loaded weight for a towing vehicle and its trailer. This includes the vehicle's fuel, passengers, and cargo. Trucks and truck/trailer combinations with an empty weight exceeding 16,000 pounds and any vehicle with a GCWR exceeding 26,000 pounds must receive clearance through the state's ports of entry managed by the Colorado State Patrol (CSP). Commercial vehicles must also clear all ports of entry that are within five miles of the route on which they are traveling, unless the operator has previously secured a clearance or obtained a special permit.

A vehicle's empty weight is captured during the titling process with the Department of Revenue (DOR). The state's registration and taxation systems rely on vehicle weight to:

determine the vehicle's base registration fees;
determine whether the vehicle must participate in the Federal Heavy Vehicle Use Tax program; and
capture the operating gross vehicle weight maximum limit to print on the registration card that is used by port of entry and law enforcement.

Depending on the vehicle's tax class, the DOR also determines in which gross vehicle weight registration type the vehicle owner will participate (i.e. private carrier or commercial carrier), or, for tax class A vehicles, reports the weight to the International Registration Plan (IRP). The IRP is an agreement between the U.S. and Canada for payment of commercial motor carrier registration fees.

Oversize vehicles. If a commercial vehicle exceeds the size or weight standards established in law, the vehicle’s operator must obtain an oversize or overweight permit from CDOT, which will allow the vehicle to operate legally on designated highways. For oversize and overweight vehicles operating on city and county roads, the operator must also obtain permission or the appropriate permit from the local government to operate. More information on commercial vehicle permits may be found on CDOT’s website.

Special permits. The Colorado Department of Transportation (CDOT) issues permits relating to the safe operation of commercial motor vehicles moving extra large loads on the state's highways. These permits include "extra legal" permits for exceptions to size and weight limitations and "super load" permits for vehicles that weigh 500,000 pounds or more or that occupy two lanes and for unladen combination vehicles that occupy two lanes. Costs for the permits vary by the weight, size, and number of trips taken by the vehicle. More information about these permits can be found at CDOT's Commercial Vehicle Permits webpage. CDOT also accepts permit applications through its online permitting portal.

Penalties. Motorists in violation of size or weight limitations are subject to fines and surcharges.

Further information. More information is available in the Legislative Council Staff Issue Brief on oversize and overweight commercial vehicles. CDOT currently maintains detailed maps and information about state highway structures with less than 14 feet and 6 inches of vertical clearance on its website.

Colorado General Assembly