Idaho Oversize & Heavy Haul Permits: Key Regulations and Compliance
Important: We are not a permit service. We do not arrange permits for carriers. The following is for informational purposes only. We also do not answer permit and escort requirements. Always read your permits and provisions sheets carefully. We cannot guarantee the accuracy of the information provided.
Idaho DOT Ph#: 208-334-8420
Transporting oversize loads in Idaho requires certain permit, safety regulations, and escort requirements. It is important to understand Idaho’s oversize load management policies, whether you are dealing with oversize freight solutions, or transporting heavy equipment.
Permit Validity & Operating Hours
- Oversize permits: Valid for five days.
- Operating Time: Most routes allow travel from 30 minutes before sunrise to 30 minutes after sunset, including weekends. Weekend daytime travel is generally allowed for oversized loads.
Restricted Travel Times & Areas
If your load exceeds 13′ wide, movement is prohibited during peak hours in major cities like Boise, Idaho Falls, Coeur d’Alene, and Twin Falls. Holiday restrictions may also apply depending on dimensions.
Legal Dimensions for Heavy Haul Trucks
- Length:
- 53′ semi-trailers allowed on the National Network.
- 48′ trailers on non-designated routes (including parts of US-12, US-93, and US-95).
- Divisible loads exceeding 48′ require an annual extra-length permit, with off-track limits (max 5.50 feet, or 3.00 feet on some mountain routes).
- Non-divisible loads can be permitted without off-track restrictions.
- Overhang: 4′ front, 15′ rear.
- Width: 8′-6″ (legal max without a permit).
- Height: 14′.
- Weight Limits:
- Gross Weight: 80,000 lbs.
- Single Axle: 20,000 lbs.
- Tandem Axle: 34,000 lbs.
- Steer Axle: 600 lbs per inch of tire width.
Divisible loads over 80,000 lbs can operate without a permit on state highways if axle weights are legal. However, Interstate travel requires an Annual Excess Weight Permit.
Routine Permit Limits
- Length: Up to 110′
- Width: Up to 16′
- Height: Up to 15′-6″
- Weight:
- Single Axle: 22,000–33,000 lbs.
- Tandem Axle: 38,500–56,000 lbs.
- Tridem Axle: 48,000–70,500 lbs.
Loads exceeding these dimensions are classified as Super Loads and require special permitting.
Escort Requirements for Oversize Loads
Proper oversize load escort services ensure safe transport.
- On 2-Lane Highways:
- Length: >100′ → 1 escort
- Overhang: >25′ rear → 1 escort
- Width:
- >12′ → 1 escort
- >14′ → 2 escorts
- >16′ → May require 3 escorts
- Height: >16′ → 1 escort
- On Interstates:
- Length: >120′ → 1 escort
- Width:
- >15′ → 1 escort
- >16′ → May require 2–3 escorts
Additional Oversize Load Safety Regulations
- All lift axles must be grounded if exceeding legal weights.
- Blades, buckets, etc. may be hauled separately, subject to approval.
Signs, Flags & Lights (Marking and Signage Requirements for Oversize Loads)
- “Oversize Load” signs: Required for all overwidth shipments.
- Flags: Needed at all four corners and extremities of overwidth loads.
- Rear overhang >4′: Requires flags.
- Overweight-only loads: Do not need signs or flags.