By Evan Reid, Founder of Haul Handbook · Updated Sep 28, 2026
ITD Commercial Vehicle Services issues Idaho's special (oversize and overweight) permits through the online Idaho Transportation Routing and Permitting System (ITRPS) at permits4idaho.com, at ports of entry, or by phone, under IDAPA 39.03.01 and Idaho Code 49-1004. Legal no-permit limits are 8 feet 6 inches wide, 14 feet high, and 80,000 pounds gross on interstates, but Idaho allows 105,500 pounds gross on its other highways, and up to 129,000 pounds on designated routes with an annual extra length/excess weight permit. A single-trip oversize permit is $30; a single-trip overweight or overweight/oversize permit is $33 plus a per-mile road use fee set by axle count and gross weight in 49-1004(2). Escort and travel-time rules depend on the route color (red, black, or white) on ITD's Pilot/Escort Vehicle Travel Requirements map.
Idaho legal limits (no permit needed at or under these)
- Width
- 8.5 ftIdaho Code 49-1010(1): 8 1/2 feet including any load. Farm tractors carried on the interstate system are limited to 9 feet without a special permit (49-1010(1)(c)). IDAPA 39.03.01.010.03 excludes mirrors, turn signals, splash and spray devices, load-induced tire bulge and similar non-cargo appurtenances from width.
- Gross weight
- 80,000 lbIdaho Code 49-1001 caps gross weight at 80,000 pounds on United States interstate and defense highways in Idaho, but at 105,500 pounds on other highways, subject to the axle-group formula W = 500((LN/N-1) + 12N + 36) and its table. Reducible loads may run above 105,500 up to 129,000 pounds on non-interstate designated routes under an annual special route permit (49-1001(1)(c) and 49-1004(4)).
- Length: Note
- Idaho Code 49-1010(3): a single motor vehicle 45 feet; a trailer or semitrailer 48 feet, but 53 feet on the national network and on access routes within one road mile of it and state highways approved by the board, and semitrailers on routes of severe curvature, deficient width or heavy traffic are held to a 65-foot overall combination; a motor vehicle with one or more trailers 75 feet; a semitrailer-trailer or double semitrailer combination 61 feet of cargo length excluding the tractor (75 feet overall when the cargo length exceeds 61 feet), or 68 feet of cargo length on the national network; stinger-steered dromedaries, boat transporters and pole or log combinations 75 feet; stinger-steered auto transporters 80 feet; non-stinger-steered auto and boat transporters 65 feet. 49-1010(4): load overhang up to 4 feet beyond the front and 10 feet beyond the end. 49-1010(6): saddlemount combinations 97 feet on the national network and 75 feet elsewhere. 49-1010(7): combinations of up to four units and 115 feet overall may run by permit on designated routes (cargo length 95 feet for a tractor with two or three trailing units, 98 feet for a truck with two trailing units).
- Off interstate limits
- 105,500 pounds gross vehicle or combination weight on highways other than the interstate and defense highways, with a single axle at 20,000 pounds and a single wheel at 10,000 pounds, and every group of two or more consecutive axles held to the 49-1001(1) formula table. A public highway agency may set lower weights on highways with limited structural capacity (49-1001(1)(a)).
Axle weight limits
Gross weight is one ceiling; each axle group carries its own limit, and a load can be legal on gross weight yet overweight on an axle. Exceeding any of these needs an overweight permit.
Scroll sideways to see every column.
Permit fees
- Single trip
- $30 (IDAPA 39.03.01.107.05: an oversize-only single trip permit is $30, and an overweight/oversize or overweight (non-divisible) single trip permit is $33. Overweight non-divisible permits also pay the road use fee in Idaho Code 49-1004(2), which for single trips is calculated and collected when the permit is issued (39.03.01.310.01). Fees are due at issuance and are refundable only if the permittee contacts Commercial Vehicle Services within two working days of the start date or the permit was issued in error.)
- Annual eligibility
- The $128 annual permit (IDAPA 39.03.01.107.05.d) covers non-divisible overweight/oversize loads at the annual overweight levels assigned by route color (39.03.01.308); red routes need a bridge analysis and a permit specific to the configuration, route and weights. Annual oversize (non-divisible) permits are $45 and, for continuous operation on black and interstate routes, allow up to 16 feet wide, 15 feet 6 inches high and 120 feet long including overhang, or 12 feet 6 inches wide on red routes (39.03.01.311.01). Annual permits bought online are $5 less. Loads over the annual levels must move on single-trip permits (39.03.01.300.06.a).
Single-trip permit fee schedule
A single-trip permit stacks a base fee with a weight-tiered maintenance fee, and the heaviest loads add a supervision fee.
Scroll sideways to see every column.
To price a specific load, try the oversize permit cost estimator, or compare every state on the national oversize permit table.
To see how these fees combine on real loads, walk through Idaho oversize permit cost worked examples.
Escort thresholds
What the escort itself has to be
Hitting the threshold is only half of it. The escort vehicle, its equipment, its driver's certification and where it rides are all regulated, and the carrier is the one holding the permit when they are not met.
- Rule scope
- A single-trip permit requires a pilot car whenever the permit's escort or restriction section says so; annual permit holders follow the Pilot/Escort Vehicle Travel and Vertical Clearance of Structures map for their size and route (IDAPA 39.03.01.306.03). A rear escort is required when the load's width keeps the driver from seeing 200 feet behind (306.12, under Idaho Code 49-940), and a third, advance pilot may be required for extreme dimensions (306.13). County permits issued by ITD follow the same escort requirements as the map.
- Police escort
- Neither the map nor IDAPA 39.03.01 sets a dimension that triggers a police escort statewide. On US-12 milepost 74 to 174 through the Nez Perce-Clearwater Forest, loads over 16 feet wide, 150,000 pounds or 150 feet long fall under U.S. Forest Service review and additional safety requirements that include ambulances and possible law enforcement escorts (39.03.01.307).
- Escort vehicle standards
- Pilot/escort vehicles are passenger cars or trucks not over 16,000 pounds, may not tow a trailer, and must display a roof-top OVERSIZE LOAD sign 12 inches high by 5 feet wide with 8-inch black letters on yellow, flashing or rotating amber lights at each end of the sign (or one amber beacon visible 500 feet), headlights and taillights on, a two-way radio good for one-half mile, and carry an 18-inch STOP/SLOW paddle, three reflective triangles, a 5-pound B,C fire extinguisher, ANSI Class 2 or 3 apparel, two spare signs, a height pole when required, a hardhat, flashlight and first aid kit (39.03.01.306).
- Convoys
- Oversize loads needing pilots may convoy up to four loads between front and rear pilot/escort vehicles, with units limited to 14 feet wide on black routes and 12 feet 6 inches on red routes, and 100 feet long on black routes, 75 feet on red routes and 120 feet on the interstate (39.03.01.304.01). Manufactured homes, modular buildings and office trailers convoy no more than two units between two pilots.
- How far ahead or behind the escort rides
- About 1,000 feet between the pilot/escort vehicle and the load in rural areas (39.03.01.306.15).
Escort rules beyond the thresholds
Knowing when you need an escort is half of it. These are the Idaho rules on who may run one, what the vehicle has to carry, and how the move is conducted.
- Rule scope
- A single-trip permit requires a pilot car whenever the permit's escort or restriction section says so; annual permit holders follow the Pilot/Escort Vehicle Travel and Vertical Clearance of Structures map for their size and route (IDAPA 39.03.01.306.03). A rear escort is required when the load's width keeps the driver from seeing 200 feet behind (306.12, under Idaho Code 49-940), and a third, advance pilot may be required for extreme dimensions (306.13). County permits issued by ITD follow the same escort requirements as the map.
- Police escort
- Neither the map nor IDAPA 39.03.01 sets a dimension that triggers a police escort statewide. On US-12 milepost 74 to 174 through the Nez Perce-Clearwater Forest, loads over 16 feet wide, 150,000 pounds or 150 feet long fall under U.S. Forest Service review and additional safety requirements that include ambulances and possible law enforcement escorts (39.03.01.307).
- Escort vehicle standards
- Pilot/escort vehicles are passenger cars or trucks not over 16,000 pounds, may not tow a trailer, and must display a roof-top OVERSIZE LOAD sign 12 inches high by 5 feet wide with 8-inch black letters on yellow, flashing or rotating amber lights at each end of the sign (or one amber beacon visible 500 feet), headlights and taillights on, a two-way radio good for one-half mile, and carry an 18-inch STOP/SLOW paddle, three reflective triangles, a 5-pound B,C fire extinguisher, ANSI Class 2 or 3 apparel, two spare signs, a height pole when required, a hardhat, flashlight and first aid kit (39.03.01.306).
- Convoys
- Oversize loads needing pilots may convoy up to four loads between front and rear pilot/escort vehicles, with units limited to 14 feet wide on black routes and 12 feet 6 inches on red routes, and 100 feet long on black routes, 75 feet on red routes and 120 feet on the interstate (39.03.01.304.01). Manufactured homes, modular buildings and office trailers convoy no more than two units between two pilots.
Conditions attached to every permit
The standing conditions Idaho writes into the permit itself, which apply whether or not they are printed on your copy.
- Carry requirement
- The permit, or evidence of intent to obtain one, must be carried in the vehicle in hard copy or digital form and shown on demand (Idaho Code 49-1004(1)(c); IDAPA 39.03.01.102.03). An operator must obtain a permit, or establish intent to obtain one by contacting a permit office and receiving a permit number, before moving (49-1004(1)(b)).
- Safety inspection
- Every vehicle, tractor, trailer and dolly moving under a special permit must have a valid annual inspection under 49 CFR 396.17 when the permit is issued, and applying for a permit self-certifies that inspection (IDAPA 39.03.01.103).
- State roadways only
- ITD special permits cover state roadways only unless a local jurisdiction has an agreement with ITD; county roads and city streets are neither granted nor implied (39.03.01.100.03).
- Port of entry stops
- All oversize vehicles must stop at all port of entry sites for inspection (39.03.01.300.02).
- Divisible load rule
- Overweight permits are issued only for non-divisible loads reduced to a practical minimum, on vehicles with five or more axles unless self-propelled vocational or towing (39.03.01.300.06); non-divisible means separating the load would compromise the vehicle's use, destroy its value, or take more than eight work hours to dismantle, with the applicant carrying the burden of proof (010.14).
- Building mover insurance
- Haulers of buildings 14 feet or more wide must carry $300,000 combined single limit when hauling their own building and $750,000 when hauling for hire (39.03.01.303.01).
- Revocation
- Permits become invalid, and the vehicle may be disqualified from reissuance for 30 days, 6 months, then 1 year on successive violations, on convictions for Part 393 equipment defects, route, signing, pilot car, lighting or travel-hour violations, axle weights more than 15 percent over, gross or bridge weight more than 7 percent over, or an FMCSA out-of-service violation (39.03.01.108).
Travel restrictions
- Daylight only
- Depends on route color. Red-coded routes are daylight travel only, stopping at 2 p.m. on Friday or the day before a holiday, with no weekend travel (IDAPA 39.03.01.305.01). On black-coded routes and the interstate, loads not over 12 feet wide, 120 feet long and 15 feet high may travel 24 hours a day, 7 days a week; larger loads follow the map, which gives them daylight travel only (305.02 and 305.03). Any permitted vehicle with more than 7 feet of front overhang is daylight-only on two-lane, two-way highways (305.07). Loads wider than 8 feet 6 inches traveling from 30 minutes after sunset to 30 minutes before sunrise, or in visibility under 500 feet, must light their extremities (39.03.01.104.02).
- Curfews
- IDAPA 39.03.01.305.08: permitted loads more than 13 feet wide may not move on state roadways from 6:00 to 9:00 a.m. and 4:00 to 6:30 p.m. local time, Monday through Friday, in the Boise valley (I-84 MP 26 to 59), Coeur d'Alene (I-90 MP 0 to 17), Idaho Falls (I-15 MP 115 to 121), the Pocatello valley (listed segments of I-15, I-15B, I-86, US-30 and US-91), Twin Falls (US-93 MP 41 to 53), and within one mile of the city limits of Eagle, Emmett, Garden City, Middleton and Star. Oversize loads moving during those hours are restricted to the right-hand lane (305.09).
- Weekend / holiday
- Holidays are New Year's Day, Memorial Day, Independence Day, Labor Day, Thanksgiving and Christmas (305.04). Red routes stop at 2 p.m. the day before a holiday and resume at sunrise the day after; on black routes, loads over the 12-foot, 120-foot or 15-foot dimensions stop before 4:00 p.m. the day preceding a holiday and resume at sunrise the day following (305.01 and 305.02).
- Wind / weather
- A permit becomes invalid en route when the roadway is under wind over 40 mph (39.03.01.102.06.d.ii).
- Additional approval
- Department approval, which may take up to 24 working hours, is required for loads over 16 feet wide on red and black routes, 18 feet wide on the interstate, 16 feet high on any route, 120 feet long off the interstate or 150 feet long on the interstate (39.03.01.305.11). Over-height loads may need 24 working hours for route evaluation (302.01).
- Daylight hours rule
- Depends on route color. Red-coded routes are daylight travel only, stopping at 2 p.m. on Friday or the day before a holiday, with no weekend travel (IDAPA 39.03.01.305.01). On black-coded routes and the interstate, loads not over 12 feet wide, 120 feet long and 15 feet high may travel 24 hours a day, 7 days a week; larger loads follow the map, which gives them daylight travel only (305.02 and 305.03). Any permitted vehicle with more than 7 feet of front overhang is daylight-only on two-lane, two-way highways (305.07). Loads wider than 8 feet 6 inches traveling from 30 minutes after sunset to 30 minutes before sunrise, or in visibility under 500 feet, must light their extremities (39.03.01.104.02).
- Weather
- Permits also become invalid when ITD, ISP or other law enforcement gives public notice of a hazardous road condition, when the driver reasonably knows of one, when a road is marked Difficult on 511, or on loss of traction from ice, snow, frost, water or mud, visibility under 500 feet, roadway obstruction, or a natural disaster (39.03.01.102.06).
- Additional approval
- Department approval, which may take up to 24 working hours, is required for loads over 16 feet wide on red and black routes, 18 feet wide on the interstate, 16 feet high on any route, 120 feet long off the interstate or 150 feet long on the interstate (39.03.01.305.11). Over-height loads may need 24 working hours for route evaluation (302.01).
Superload and beyond-permit review
Loads past the standard single-trip permit thresholds get individual state review rather than an off-the-shelf permit.
Idaho's rule and statute do not use the term superload or set a single superload weight. The escalation points instead: a traffic control plan prepared by a licensed engineer or ATSSA-certified supervisor for two-lane highways when a load exceeds 18 feet wide, 150 feet long or 16 feet high (IDAPA 39.03.01.300.09 and .10); bridge approval when a single or steer axle exceeds 35,000 pounds (315.02); department bridge analysis of up to 3 business days for a vehicle or combination up to 250,000 pounds and up to 10 business days above 250,000 pounds (316.01); and a mandatory third-party bridge analysis above 800,000 pounds (316.02).
Requests above routinely allowed weights need additional department review and may need an engineering analysis where structures are involved (315.01). Third-party analysis is also required for multi-configuration or multi-route requests and at the department's discretion, at the applicant's cost (316.01, .04 to .06). On US-12 through the Nez Perce-Clearwater Forest, loads over 16 feet wide, 150,000 pounds or 150 feet long, or needing over 12 hours to transit, are subject to U.S. Forest Service review (307.01).
More Idaho permit rules
- Single trip fee note
- IDAPA 39.03.01.107.05: an oversize-only single trip permit is $30, and an overweight/oversize or overweight (non-divisible) single trip permit is $33. Overweight non-divisible permits also pay the road use fee in Idaho Code 49-1004(2), which for single trips is calculated and collected when the permit is issued (39.03.01.310.01). Fees are due at issuance and are refundable only if the permittee contacts Commercial Vehicle Services within two working days of the start date or the permit was issued in error.
- Annual permit eligibility
- The $128 annual permit (IDAPA 39.03.01.107.05.d) covers non-divisible overweight/oversize loads at the annual overweight levels assigned by route color (39.03.01.308); red routes need a bridge analysis and a permit specific to the configuration, route and weights. Annual oversize (non-divisible) permits are $45 and, for continuous operation on black and interstate routes, allow up to 16 feet wide, 15 feet 6 inches high and 120 feet long including overhang, or 12 feet 6 inches wide on red routes (39.03.01.311.01). Annual permits bought online are $5 less. Loads over the annual levels must move on single-trip permits (39.03.01.300.06.a).
- Annual permit details: covers: annual oversize black and interstate
- 16 ft wide, 15 ft 6 in high, 120 ft long including load overhang
- Annual permit details: note
- Annual overweight permit holders must file quarterly reports of laden-only miles at the permitted weight level, even when reporting zero miles, and the account is suspended if a report is not submitted (39.03.01.310). Annual extra length/excess weight permits up to 129,000 pounds are valid only on the routes on the Designated Routes Up to 129,000 Pound Map, which travels with the permit (39.03.01.203.01).
- Permitted weight notes: allowances
- IDAPA 39.03.01.308 sets seven overweight levels for annual overweight/oversize permits, color-coded by route; red routes contain posted bridges and require a department analysis before an annual permit for a specific configuration, route and weights. The maximum overweight levels may not exceed 800 pounds per inch of tire width (39.03.01.300.07).
- Permitted weight notes: over cap rule
- Vehicles or loads over the axle, axle-group or gross weights of any annual overweight level must move on an approved single-trip permit (39.03.01.300.06.a). A single or steer axle over 35,000 pounds needs bridge approval (39.03.01.315.02).
- Escort notes: rule scope
- A single-trip permit requires a pilot car whenever the permit's escort or restriction section says so; annual permit holders follow the Pilot/Escort Vehicle Travel and Vertical Clearance of Structures map for their size and route (IDAPA 39.03.01.306.03). A rear escort is required when the load's width keeps the driver from seeing 200 feet behind (306.12, under Idaho Code 49-940), and a third, advance pilot may be required for extreme dimensions (306.13). County permits issued by ITD follow the same escort requirements as the map.
- Escort notes: police escort
- Neither the map nor IDAPA 39.03.01 sets a dimension that triggers a police escort statewide. On US-12 milepost 74 to 174 through the Nez Perce-Clearwater Forest, loads over 16 feet wide, 150,000 pounds or 150 feet long fall under U.S. Forest Service review and additional safety requirements that include ambulances and possible law enforcement escorts (39.03.01.307).
- Escort notes: escort vehicle standards
- Pilot/escort vehicles are passenger cars or trucks not over 16,000 pounds, may not tow a trailer, and must display a roof-top OVERSIZE LOAD sign 12 inches high by 5 feet wide with 8-inch black letters on yellow, flashing or rotating amber lights at each end of the sign (or one amber beacon visible 500 feet), headlights and taillights on, a two-way radio good for one-half mile, and carry an 18-inch STOP/SLOW paddle, three reflective triangles, a 5-pound B,C fire extinguisher, ANSI Class 2 or 3 apparel, two spare signs, a height pole when required, a hardhat, flashlight and first aid kit (39.03.01.306).
- Escort notes: convoys
- Oversize loads needing pilots may convoy up to four loads between front and rear pilot/escort vehicles, with units limited to 14 feet wide on black routes and 12 feet 6 inches on red routes, and 100 feet long on black routes, 75 feet on red routes and 120 feet on the interstate (39.03.01.304.01). Manufactured homes, modular buildings and office trailers convoy no more than two units between two pilots.
- Escort notes: spacing
- About 1,000 feet between the pilot/escort vehicle and the load in rural areas (39.03.01.306.15).
- Escort notes: forest exception
- No pilot is required on the first movement from the forest of tree-length logs or poles up to 110 feet overall (39.03.01.306.14).
- Escort notes: certification note
- No pilot/escort driver certification requirement appears in IDAPA 39.03.01 or on the pilot/escort map.
- Seasonal permits note
- No seasonal permit class is sold. The seasonal rule runs the other way: during spring breakup ITD may post state roadways down to 16,000, 14,000 or 12,000 pounds per axle, cap special-permit width at 12 feet 6 inches on restricted two-lane sections, restrict trucks and buses of 10,000 pounds or more to 30 mph in marked zones, and suspend normal overweight permit limits, while still permitting non-divisible overweight loads with tires at least 10 inches wide and axle weights of 10,000 pounds (two single wheels) or 14,000 pounds (four or more tires) (IDAPA 39.03.01.106).
- Permit conditions: carry requirement
- The permit, or evidence of intent to obtain one, must be carried in the vehicle in hard copy or digital form and shown on demand (Idaho Code 49-1004(1)(c); IDAPA 39.03.01.102.03). An operator must obtain a permit, or establish intent to obtain one by contacting a permit office and receiving a permit number, before moving (49-1004(1)(b)).
- Permit conditions: safety inspection
- Every vehicle, tractor, trailer and dolly moving under a special permit must have a valid annual inspection under 49 CFR 396.17 when the permit is issued, and applying for a permit self-certifies that inspection (IDAPA 39.03.01.103).
- Permit conditions: state roadways only
- ITD special permits cover state roadways only unless a local jurisdiction has an agreement with ITD; county roads and city streets are neither granted nor implied (39.03.01.100.03).
- Permit conditions: port of entry stops
- All oversize vehicles must stop at all port of entry sites for inspection (39.03.01.300.02).
- Permit conditions: divisible load rule
- Overweight permits are issued only for non-divisible loads reduced to a practical minimum, on vehicles with five or more axles unless self-propelled vocational or towing (39.03.01.300.06); non-divisible means separating the load would compromise the vehicle's use, destroy its value, or take more than eight work hours to dismantle, with the applicant carrying the burden of proof (010.14).
- Permit conditions: building mover insurance
- Haulers of buildings 14 feet or more wide must carry $300,000 combined single limit when hauling their own building and $750,000 when hauling for hire (39.03.01.303.01).
- Permit conditions: revocation
- Permits become invalid, and the vehicle may be disqualified from reissuance for 30 days, 6 months, then 1 year on successive violations, on convictions for Part 393 equipment defects, route, signing, pilot car, lighting or travel-hour violations, axle weights more than 15 percent over, gross or bridge weight more than 7 percent over, or an FMCSA out-of-service violation (39.03.01.108).
- Permit conditions: liability and indemnity
- The permittee assumes all responsibility for injury or damage caused by the permitted move and holds ITD harmless (39.03.01.109).
- Overweight fee schedule note
- Idaho prices overweight non-divisible moves by a per-mile road use fee on top of the flat $33 single-trip permit, keyed to axle count and gross weight (Idaho Code 49-1004(2)): Column 1 starts at 4 cents per mile and rises 4 cents per 2,000 pounds; Column 2 (5 or more axles, from 131,001 pounds for 5 axles) starts at $1.02 per mile and rises 7 cents per 2,000 pounds. Annual overweight permit holders report laden-only miles quarterly instead of paying at issuance (IDAPA 39.03.01.310). Separately, vehicles registered for 105,500 pounds that run up to 129,000 pounds on designated routes pay the Idaho Code 49-434 registration fee for the higher weight in addition to the $45 annual extra length/excess weight permit (49-1004(5)).
| Axle group | Note |
|---|---|
| Yellow routes (single / tandem / tridem) | 22,500 / 38,000 / 48,000 pounds, or the equivalent under W = 560((LN/N-1) + 12N + 36). |
| Orange routes (single / tandem / tridem) | 24,000 / 41,000 / 51,500 pounds, or the equivalent under W = 600((LN/N-1) + 12N + 36). |
| Green routes (single / tandem / tridem) | 25,500 / 43,500 / 54,500 pounds, or the equivalent under W = 640((LN/N-1) + 12N + 36). |
| Blue routes (single / tandem / tridem) | 27,000 / 46,000 / 57,500 pounds, or the equivalent under W = 675((LN/N-1) + 12N + 36). |
| Purple routes (single / tandem / tridem) | 30,000 / 51,500 / 64,500 pounds, or the equivalent under W = 755((LN/N-1) + 12N + 36). |
| Black routes (single / tandem / tridem) | 33,000 / 56,000 / 70,500 pounds, or the equivalent under W = 825((LN/N-1) + 12N + 36). |
The Idaho permit office
- Apply or log in (Idaho Transportation Routing and Permitting System (ITRPS); IDAPA 39.03.01.102.02 allows applications online, at ports of entry, or with Commercial Vehicle Services)
- permits4idaho.com/Login.aspx
- Agency
- Idaho Transportation Department, Division of Motor Vehicles, Commercial Vehicle Services (special permits and commercial registration)
- Hours
- Monday to Friday, 8:00 a.m. to 5:00 p.m. Mountain Time (Commercial Vehicle Services phone hours)
- Notes
- The ITRPS login page tells customers to contact the permit office at 208-872-3163 to create an account, with or without a USDOT number; the same number is the Commercial Vehicle Services line on ITD's commercial vehicle page, because one unit handles both special permits and commercial registration. Special permit rules, maps and permit attachments are posted under Helpful Links in ITRPS.
Legal limits without a permit
Idaho uses the common national width and a fixed height limit, and the interstate gross limit matches the federal one. Off the interstate, Idaho allows more gross weight, subject to axle limits and the bridge formula. Reducible loads can run heavier still on the designated routes map with an annual extra length and excess weight permit.
Single-trip and annual permits
Single-trip permits split into oversize-only and overweight classes, and overweight single trips pay the road use fee at issuance. Annual permits cover non-divisible oversize loads, overweight loads at the levels assigned by route color, and extra length or excess weight on designated routes. Annual overweight holders report laden miles every quarter, even when the answer is zero, and annual permits bought online cost less.
Route colors, escorts and travel hours
ITD's Pilot/Escort Vehicle Travel Requirements map marks each highway red, black or white. Red routes need pilots at smaller widths and allow daylight travel only, with no weekend moves. Black routes and the interstate allow wider loads without pilots, and loads within the black-route dimensions may travel around the clock. Rush-hour curfews apply to very wide loads in the larger metro areas.
When a move needs more review
Idaho does not define a superload. Instead, review steps up with size and weight: an engineered traffic control plan for the largest loads on two-lane roads, bridge approval for heavy single axles, and department or third-party bridge analysis as gross weight climbs. On US-12 through the Nez Perce-Clearwater Forest, the Forest Service reviews the biggest loads.
How to read this page
A value reading "Not confirmed" means we could not verify the figure on an official agency page at review time, so it stays open rather than guessed. Superload moves above the standard permit thresholds get individual review by the state; contact the permit office named on this page. For the rest of the Idaho permit stack, see Idaho trucking permits.