When an oversize permit is required in New Mexico

Dec. 12, 2025, 6:16 p.m.
New Mexico requires an Oversize Permit whenever a commercial vehicle or load exceeds the legal size limits established by the New Mexico Department of Transportation (NMDOT). These limits apply to truck tractors, trailers, combinations, and loads (including non-divisible loads such as machinery, equipment, or structures). Below is the full breakdown of when a permit is required.
Oversize permit in New Mexico

1. Legal Size Limits in New Mexico

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

A. Width Limits

  • Legal width: 8 feet 6 inches (102”)

  • Anything over 8'6" requires an oversize permit.

  • Mirrors and minor safety devices do not count toward width.

B. Height Limits

  • Legal height: 14 feet

  • Any vehicle or load above 14 feet high requires a permit.

New Mexico has many low-clearance structures, so height routing is critical.

C. Length Limits

Length varies by vehicle type:

Single Vehicle

  • Legal length: 45 feet

Truck + Trailer Combinations

  • Tractor–semitrailer: 65 feet

  • Truck–trailer: 65 feet

  • Twin trailers (doubles): 28'6" each trailer

When a permit is required

A permit is needed any time a vehicle or combination exceeds:

  • 65 feet total length
    (unless operating under special configurations allowed on designated routes)

D. Overhang Limits

  • Legal front overhang: 3 feet

  • Legal rear overhang: 4 feet

A permit is required if overhang exceeds these limits.

2. When Oversize Permits Are Required by Type of Load

A. Non-Divisible Loads

A permit is required when the load:

  • Cannot be reduced in size without damaging it

  • Includes machinery, construction equipment, modular buildings, tanks, etc.

If the non-divisible load exceeds any legal dimension → permit required.

B. Divisible Loads

Divisible loads cannot be oversized in New Mexico.

New Mexico generally does not grant oversize permits for:

  • Palletized freight

  • Aggregates

  • Lumber

  • Pipe bundles

  • General commodities

If a divisible load exceeds legal dimensions → it must be reduced.

3. When Special Oversize Permits Are Required

A standard single-trip permit is required when exceeding legal limits, but special oversize authority is needed when exceeding:

Superload thresholds:

You must undergo engineering review if your load is:

  • Over 20 feet wide

  • Over 16 feet high

  • Over 120 feet long

  • Combined weight over 200,000 lbs (also triggers overweight review)

Superloads cannot travel without an approved route and escort plan.

4. When Escort (Pilot Car) Requirements Trigger a Permit

A permit is also required whenever escort rules apply, such as:

  • Width over 12 feet

  • Height over 15 feet

  • Length over 90–120 feet (depending on route)

Even if only one dimension is exceeded → permit required.

5. When Temporary Movement Requires an Oversize Permit

You must obtain an oversize permit even for temporary or short moves when transporting:

  • Construction equipment between job sites

  • Agricultural equipment on highways

  • Modular or manufactured housing

  • Wellfield or oilfield equipment

  • Heavy mining or energy machinery

Even “short distance” moves require permits if over legal size.

6. Summary — When You MUST Have an Oversize Permit in New Mexico

You need an oversize permit if ANY of the following are true:

  • Width > 8'6"

  • Height > 14'

  • Length > 65' (vehicle or combination)

  • Overhang > 3' front or 4' rear

  • Transporting a non-divisible oversize load

  • Moving equipment over legal limits for construction, agriculture, or oilfields

  • Exceeding thresholds that trigger escort/pilot car requirements

  • Operating a superload exceeding extreme dimensions

If even one legal dimension is exceeded → permit required.

 

https://www.dot.nm.gov/planning-research-multimodal-and-safety/modal/ports-of-entry/