Permits
Idaho Oversize Permits are valid for 5 days.

Operating Time
Travel is allowed one-half hour before sunrise to one-half hour after sunset, including Saturdays and Sundays (majority of routes). Up to and including 10′ wide, 120′ long or 14’6 high, travel is allowed 24/7 (majority of routes) with lighting as specified on the Idaho oversize permit. Weekend travel is allowed on the majority of routes during daytime hours.

Restrictions
If the load is over 13′ wide, movement is prohibited between 6:30 a.m. – 8:30 a.m., and 4:00 p.m. – 6:00 p.m. in most major cities. Holiday travel restrictions depend on dimension and route.

Speed Limit

Interstate 70 mph. Non-interstate 65 mph. Unless otherwise specified on permit.

Legal Dimensions
The vehicle must have the following characteristics:

Width: 8’6″
Height: 14′
Length: 53′ semi-trailer on National Network, 48′ trailer on non-National Network (“non-designated”)
Overhang: 4′ front, 10′ rear
Weight: 80,000 Gross; Single – 20,000; Tandem – 34,000; Tridem – depends on spacing; Steer – 600 pounds per inch of tread width (13,200 pounds with 11″ tires).
*Note: Several 2-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. For divisible loads, trailers exceeding 48’ are only allowed with an annual extra length permit, and the tractor-trailer off-track measurement must not exceed 5’6″ (3.00 on a few mountain routes). Non-divisible loads are covered by a single or annual permit, without regard to off-track amount.

Routine Idaho Oversize Permit Limits
Width: 16′
Height: 15’6″
Length: 110′.
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)
Note*: Group weight maximums depend on route classification, with Interstate routes getting the highest. Loads exceeding these dimensions are considered Super Loads.

Escorts
Width: On 2-Lane Highways: Over 12′ – 1 escort pilot car; over 14′ – 2 escort pilot cars; over 16′ – may require 3 escort pilot cars; On Interstate System: Over 15′ – 1 escort pilot car; over 16′ – may require 2 or 3 escort pilot cars
Height: Over 16′ – 1 escort pilot car.
Length: On 2-Lane Highways: Over 100′ – 1 escort pilot car ; On Interstate System: Over 120′ – 1 escort pilot car; Overhang: Over 25′ rear – 1 escort pilot car.

Security Measures
“Oversize Load” signs are required on all permit loads. Flags are required on all four corners and extremities of oversized loads.