Permits
Idaho oversize permits are valid for five days.
Operating Time
One half hour before sunrise to one-half hour after sunset, including Saturdays and Sundays (majority of routes). Up to and including 10′ wide, 110′ long or 14′-6″ high, travel is allowed 24/7 (majority of routes) with lighting as specified on permit. Weekend travel is allowed on majority of routes during daytime hours.
Restricted Travel
If over 13′ wide, movement prohibited between 6:30 am – 8:30 am, 11:30 am – 1:30 pm, and 4:00 pm – 6:00 pm in Boise, Caldwell, Coeur d’Alene, Idaho Falls, Lewiston, Nampa, Pocatello, Twin Falls, Garden City and Chubbuck. Holiday travel restrictions may depend on dimension.
Legal Dimensions
Length:
53′ semi-trailer on National Network
48′ trailer on non-N.N. (“non-designated”)
Note: Several two-lane highways in Idaho are non-designated, including US-12 except in the Lewiston to Spalding, US-93 from Salmon to Challis, and US-95 from Council to Grangeville.
Divisible loads, trailers exceeding 48’ are only allowed with an annual extra length permit, and the tractor-trailer off-track measurement must not exceed 5.50 feet (3.00 on a few mountain routes)
Non-divisible loads are covered by single or annual permit, without regard to off-track amount.
Overhang: 4′ front, 15′ rear
Width: 8′-6″
Height: 14′
Weight:
80,000 Gross
Single – 20,000
Tandem – 34,000
Tridem – depends on spacings
Steer – 600 pounds per inch of tread width (13,200 pounds with 11″ tires)
Divisible Loads Exceeding 80,000: You can exceed 80,000 gross without a permit on state highways as long as you are legal on all axle/group weights and you are licensed for at least the amount of your gross weight. However, if you need any Interstate routes, you will need to get an Annual Excess Weight Permit.
Routine Permit Limits
Length: 110′
Width: 16′
Height: 15′-6″
Weight:
Single – 33,000 to 22,000*
Tandem – 56,000 to 38,500*
Tridem – 70,500 to 48,000*
Steer – 600 pounds
per inch of tread width (13,200 pounds for 11″ tires)
* Group weight maximums depend on route classification, with Interstate routes getting the highest.
Loads exceeding these dimensions or are considered as Super Loads.
Escorts
On 2-Lane Highways:
Length: Over 100′ – one escort
Overhang: Over 25′ rear – one escort.
Width:
Over 12′ – one escort
over 14′ – two escorts
over 16′ – may require three escorts
Height: Over 16′ – one escort.
On Interstate System:
Length: Over 120′ – one escort.
Overhang: Over 25′ rear – one escort.
Width:
Over 15′ – one escort
Over 16′ – may require two or three escorts
Height: Over 16′ – one escort.
Miscellaneous
All lift axles must be on the ground if exceeding legal axle weights. Blades, buckets, etc. may be taken off and hauled on the same load, depending on route and situation. State will determine on a case-by-case basis.
Signs, Flags & Lights
Requirements are specified on Idaho permit. “Oversize Load” signs are required on all overwidth loads. Flags are required on all four corners and extremities of overwidth loads and on rear overhang exceeding 4′. Overweight only loads do not require signs or flags.
