Question 1

What is legal without a permit?

Accepted Answer

Legal size: Legal limits are 8′6″ wide and 14′ high. Length rules differ for single trucks, trailers, the National Network, overhang and route colors. Weight limits: Gross weight alone does not settle it in Idaho. Check tire width and rating, axle and group spacing, registration, route capacity and bridge records. Axle limits: legal and with a permit: Legal: single 20,000 lb, tandem 34,000 lb. With a permit: single 33,000 lb, tandem 56,000 lb, tridem 70,500 lb. Legal figures: Idaho Code 49-1001 sets 20,000 lb per single axle and 34,000 lb for two axles 4′–8′ apart; the rules repeat them as the axle caps for divisible permits over 80,000 lb on Interstate and National Network routes. Permit weights shown are the black-route level for annual overweight permits; yellow, orange, green, blue and purple routes allow less, and red routes need an analysis. Never more than 800 lb per inch of tire width. Any single or steer axle over 35,000 lb needs bridge approval. Heavier than the annual levels: single-trip permit.

Question 2

Which permit do you need?

Accepted Answer

Roads & authorities: ITD permits cover the state-highway sections named on the permit. County and city roads need local approval. Check route maps and bridge capacity for every segment. When a permit is needed: Loads over legal size, or nondivisible loads over legal weight, need an ITD permit before moving. Oversize, overweight, extra-length, self-propelled, farm, disabled-vehicle and emergency permits differ. Annual limits and larger loads: Annual permits go up to 16′ wide, 15′6″ high and 110′ long on black and Interstate routes, and less on red routes. Very wide, tall, heavy or long loads need specialist review. Additional ITD approval: Extra ITD approval, which can take up to 24 working hours, is needed for loads over: 16′ wide on red- or black-coded routes. 18′ wide on Interstates. 16′ high on any route. 120′ long off the Interstate. 150′ long on the Interstate. Traffic control plan: On two-lane highways, a traffic control plan is required above 18′ wide, 150′ long or 16′ high. A licensed engineer or ATSSA-certified traffic control supervisor prepares it, showing: Pull-off spots and mileposts for traffic relief. How pilot cars and traffic control staff are used. Railroad crossings and their emergency contacts. How emergency vehicles get around the load. Bridge analysis: Weights beyond routine permit levels need ITD review and may need an engineering analysis of the bridges on the route. Any single or steer axle over 35,000 lb needs bridge approval. Up to 3 business days for analysis up to 250,000 lb; up to 10 business days above that. Over 800,000 lb, multiple configurations or multiple routes: a third party does the analysis at your cost. Overweight permit basics: Overweight permits are for non-divisible loads over legal axle weights or 80,000 lb, reduced to a practical minimum. Five or more axles required, except self-propelled vocational vehicles or vehicles towing the load. No more than 800 lb per inch of tire width. Weights above the annual permit levels need a single-trip permit. Overheight route check: Overheight permits depend on the vertical clearance of every structure on the route; ITD may require at least 24 working hours to evaluate the route. 16′6″ or more: advance notice may be needed where traffic signals are on the route. Over 16′6″: contact the local utility companies about power lines. A cash bond may be required when the state expects costs to provide clearance. County and city roads: An ITD permit covers only the state roadways described on it, unless ITD has an agreement with the local highway jurisdiction. It grants no right to use county highways or city streets. ITD permit fees: ITD's current permit fees: Oversize only, single trip: $30. Overweight or overweight/oversize (non-divisible) single trip: $33, plus the road use fee set by Idaho Code 49-1004(2). Many annual permits: $45; overweight/oversize annual: $128. Reissue or transfer: $15; annual permits bought online are $5 less.

Question 3

What does the permit cost?

Accepted Answer

Example agency fee: $30 for a nondivisible load 8′7″ wide, 13′ high and 70′ long at 72,000 lb gross, on a five-axle truck with a 48′ trailer, for 100 miles in Idaho. Enter your own load in the calculator below. What the fee covers: Idaho's fee depends on the permit product and the loaded vehicle. The calculator itemizes the published charges it can price. Local permits, escorts, tolls, payment charges and ODPermit services are separate.

Question 4

When do you need pilot cars?

Accepted Answer

Height pole: The front pilot car leading any load over 16′ high runs a non-metallic height pole. The pole must be non-conductive, non-destructive and have a flexible tip. When pilot cars are needed: Single-trip permits list the pilot cars required. Annual permit holders follow the Pilot/Escort Vehicle Travel map for their size and route. In general: A front pilot car may lead the load where it cannot stay within its lane. A rear pilot car is needed when the load's width blocks the driver's view 200′ to the rear. A third, advance pilot car may be required when opposing traffic must be held at turnouts and intersections. Keep about 1,000′ between pilot car and load in rural areas. Pilot car: A passenger car or truck no heavier than 16,000 lb, not towing a trailer, with: Roof-top OVERSIZE LOAD sign, 12″ by 5′, 8″ black letters on yellow, shown only while escorting. Flashing or rotating amber lights at each end of the sign, or one amber beacon visible from 500′. Headlights and taillights on while escorting. Two-way radio good for half a mile. 18″ STOP/SLOW paddle, three reflective triangles, 5 lb B:C extinguisher, ANSI Class 2 or 3 vest by day (Class 3 at night), two spare signs, valid driver's license, hardhat, flashlight, first aid kit. Convoys: Loads that each need a pilot car (except overwidth manufactured homes, office trailers and modular buildings) may convoy with pilot cars front and rear, up to four loads between them. Width limit in a convoy: 14′ on black routes, 12′6″ on red routes. Length limit in a convoy: 100′ on black routes, 75′ on red routes, 120′ on Interstates. Manufactured homes, office trailers and modular buildings: no more than two units between pilot cars, about 1,000′ apart. On any oversize move: A lead escort may be needed where the load cannot remain in its lane. A rear escort is required when the load blocks the driver's 200-ft rear view. An advance third car may be assigned to hold opposing traffic; these are route and visibility conditions, not automatic extra cars. Over 8′6″ wide: Red-coded routes: 1 front pilot car. Black-coded routes: no pilot car from the mapped dimensional triggers. White-coded Interstate routes: no pilot car from the mapped dimensional triggers. Over 10′ wide: Red-coded routes: 1 front and 1 rear pilot cars. Black-coded routes: no pilot car from the mapped dimensional triggers. White-coded Interstate routes: no pilot car from the mapped dimensional triggers. Over 12′ wide: Red-coded routes: 1 front and 1 rear pilot cars. Black-coded routes: 1 front pilot car. White-coded Interstate routes: no pilot car from the mapped dimensional triggers. Over 12′6″ wide: Red-coded routes: no pilot car from the mapped dimensional triggers. Black-coded routes: 1 front pilot car. White-coded Interstate routes: no pilot car from the mapped dimensional triggers. Above 12 ft 6 in wide, the red-route width table ends. ITD must assign the red-route crew; the black and Interstate width bands shown continue through 18 ft. Over 14′ wide: Red-coded routes: no pilot car from the mapped dimensional triggers. Black-coded routes: 1 front and 1 rear pilot cars. White-coded Interstate routes: no pilot car from the mapped dimensional triggers. Above 12 ft 6 in wide, the red-route width table ends. ITD must assign the red-route crew; the black and Interstate width bands shown continue through 18 ft. Over 15′ wide: Red-coded routes: no pilot car from the mapped dimensional triggers. Black-coded routes: 1 front and 1 rear pilot cars. White-coded Interstate routes: 1 rear pilot car. Above 12 ft 6 in wide, the red-route width table ends. ITD must assign the red-route crew; the black and Interstate width bands shown continue through 18 ft. Over 16′ wide: Red-coded routes: no pilot car from the mapped dimensional triggers. Black-coded routes: 1 front and 1 rear pilot cars. White-coded Interstate routes: 1 rear pilot car. Above 12 ft 6 in wide, the red-route width table ends. ITD must assign the red-route crew; the black and Interstate width bands shown continue through 18 ft. Additional approval applies above 16 ft wide on red/black routes, above 18 ft wide on Interstates, above 16 ft high on any route, above 120 ft long off Interstates, or above 150 ft long on Interstates. The permit can add escorts. If the route uses US 12 mileposts 74–174 through the Nez Perce–Clearwater Forest, these dimensions or weight require Forest Service review, an ambulance and possible law-enforcement escort. The permit sets the accompanying team and travel time. Over 18′ wide: Additional approval applies above 16 ft wide on red/black routes, above 18 ft wide on Interstates, above 16 ft high on any route, above 120 ft long off Interstates, or above 150 ft long on Interstates. The permit can add escorts. Above 18 ft wide, the posted map does not assign a standard width crew. ITD assigns the team to the load and route; the length and pole checks shown do not settle the width assignment. If the route uses US 12 mileposts 74–174 through the Nez Perce–Clearwater Forest, these dimensions or weight require Forest Service review, an ambulance and possible law-enforcement escort. The permit sets the accompanying team and travel time. Over 16′ high: Red-coded routes: 1 front (height pole required) pilot car. Black-coded routes: 1 front (height pole required) pilot car. White-coded Interstate routes: 1 front (height pole required) pilot car. Additional approval applies above 16 ft wide on red/black routes, above 18 ft wide on Interstates, above 16 ft high on any route, above 120 ft long off Interstates, or above 150 ft long on Interstates. The permit can add escorts. Over 75′ long: Red-coded routes: 1 front pilot car. Black-coded routes: no pilot car from the mapped dimensional triggers. White-coded Interstate routes: no pilot car from the mapped dimensional triggers. Over 120′ long: Red-coded routes: 1 front pilot car. Black-coded routes: 1 front pilot car. White-coded Interstate routes: no pilot car from the mapped dimensional triggers. Additional approval applies above 16 ft wide on red/black routes, above 18 ft wide on Interstates, above 16 ft high on any route, above 120 ft long off Interstates, or above 150 ft long on Interstates. The permit can add escorts. Over 150′ long: Additional approval applies above 16 ft wide on red/black routes, above 18 ft wide on Interstates, above 16 ft high on any route, above 120 ft long off Interstates, or above 150 ft long on Interstates. The permit can add escorts. Red-coded routes: 1 front pilot car. Black-coded routes: 1 front pilot car. White-coded Interstate routes: no pilot car from the mapped dimensional triggers. If the route uses US 12 mileposts 74–174 through the Nez Perce–Clearwater Forest, these dimensions or weight require Forest Service review, an ambulance and possible law-enforcement escort. The permit sets the accompanying team and travel time.

Question 5

When can you move?

Accepted Answer

Travel hours: Idaho hours depend on the route color (red, black or Interstate), the load size, holidays, weekends, spring breakup, hazards and the permit. 24/7 or daylight: Black and Interstate routes allow 24/7 travel only within their size limits. Red routes and larger loads move in daylight or on the permit's hours. Current route restrictions: Check holidays, weekends, spring breakup, ice, snow and frost, visibility, 511 and posted limits, Forest Service rules on US-12, construction, and ITD's current route and weight records. Hours by route color: Travel hours depend on the route color on ITD's pilot/escort map: Red routes: daylight travel until 2 p.m. Friday or the day before a holiday, no Saturday or Sunday travel; resume at sunrise Monday or the day after the holiday. Black routes: loads not over 12′ wide, 120′ long and 15′ high may move 24/7; larger loads follow the map and stop before 4 p.m. the day before a holiday. Interstates: loads not over 12′ wide, 120′ long or 15′ high may move 24/7; larger loads follow the map. Single-trip permits may allow different travel times. Rush-hour restrictions: Loads over 13′ wide may not move 6–9 a.m. or 4–6:30 p.m. Monday–Friday at these places (mileposts or within 1 mile of city limits), unless the permit says otherwise: Boise valley I-84 MP 26–59; Eagle, Emmett, Garden City, Middleton, Star. Coeur d'Alene I-90 MP 0–17. Idaho Falls I-15 MP 115–121. Pocatello valley (I-15, I-15B, I-86, US-30, US 91 segments). Twin Falls US 93 MP 41–53. When moving during those hours where allowed, stay in the far right lane. Permit void in bad conditions: A permit becomes invalid en route when hazardous conditions exist, including: Ice, snow, frost, water or mud causing loss of traction. Wind over 40 mph. Visibility under 500′. Road marked “Difficult” on 511. Road obstructed or under a natural disaster. Spring breakup: During spring breakup ITD may post axle limits of 16,000, 14,000 or 12,000 lb. On weight-restricted two-lane roads, permit width is capped at 12′6″. Overweight permits there are for non-divisible loads only, with 10″+ tires on all wheels, no more than 10,000 lb on a single axle with two single wheels and 14,000 lb on a single axle with four or more tires. Holiday travel limits: Red-route loads stop at 2 p.m. the day before these holidays; larger loads on black routes stop by 4 p.m. the day before. Travel resumes at sunrise the day after. Only the fixed-date holidays are listed; Memorial Day, Labor Day and Thanksgiving also apply. New Year's Day (Jan 1, 2026), Independence Day (Jul 4, 2026), Christmas (Dec 25, 2026), New Year's Day (Jan 1, 2027), Independence Day (Jul 4, 2027), Christmas (Dec 25, 2027).

What is legal without a permit?

General width: 8′6″

Loaded height: 14′

NN semitrailer: 48′

Overall length: No NN cap*

Interstate weight: 80,000 lb*

Legal size

Weight limits

Axle limits: legal and with a permit

Where each requirement starts

Width 8′6″: Legal width

Width 12′: Daylight only · black/white routes

Width 12′6″: Red-route annual cap

Width 13′: Rush-hour ban

Width 16′: ITD approval

Width 18′: Traffic control plan

Height 14′: Legal height

Height 15′: End of 24/7 travel

Height 15′6″: Annual permit cap

Height 16′: Height pole · ITD approval

Height 16′6″: Utility contact

Length 45′: Legal single vehicle

Length 53′: Legal semitrailer (NN)

Length 120′: ITD approval off Interstate

Length 150′: ITD approval · traffic plan

Overhang 4′ front: Legal front overhang

Overhang 10′ rear: Legal rear overhang

Overhang 4′ rear: Flags and lights on overhang

Overhang 7′ front: Daylight only on two-lane

Weight 80,000 lb: Legal gross on Interstates

Weight 105,500 lb: Legal gross off Interstates

Weight 129,000 lb: Designated-route cap

Weight 250,000 lb: Longer bridge analysis

Weight 800,000 lb: Third-party bridge analysis

Which permit do you need?

Roads & authorities

When a permit is needed

Annual limits and larger loads

Additional ITD approval

Traffic control plan

Bridge analysis

Overweight permit basics

Overheight route check

County and city roads

ITD permit fees

What does the permit cost?

Example agency fee

What the fee covers

When do you need pilot cars?

Height pole

When pilot cars are needed

Pilot car

Convoys

On any oversize move

Over 8′6″ wide

Over 10′ wide

Over 12′ wide

Over 12′6″ wide

Over 14′ wide

Over 15′ wide

Over 16′ wide

Over 18′ wide

Over 16′ high

Over 75′ long

Over 120′ long

Over 150′ long

When can you move?

Travel hours

24/7 or daylight

Current route restrictions

Hours by route color

Rush-hour restrictions

Permit void in bad conditions

Spring breakup

Holiday travel limits

Signs, flags and lights

Signs, flags and gear

Flags and lights on the load

OVERSIZE LOAD signs

What the driver carries

Turn the estimate
into a permitted move.