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Idaho Oversize Permits
Legal size/weight limits, escort thresholds, travel restrictions, and permit office contact for Idaho.
These figures are a reference summary of publicly published state rules, not a substitute for a state-issued permit and not legal advice. Rules change — always confirm current limits and requirements directly with the state permit office before you plan or run a move. Last verified: 2026-07-16. Oversize Ops is NOT responsible and CANNOT be held liable for decisions made from this reference. Official source ↗
Legal Maximum Dimensions (no permit required)
- Width
- 8.5ft (102in)
- Height
- 14ft (168in)
- Max semitrailer length
- 53ft on designated routes · 48ft elsewhere
- Gross Weight
- 80,000 lbs
- Single Axle
- 20,000 lbs
- Tandem Axle
- 34,000 lbs
Idaho Code 49-1010: the height of a vehicle including its load may not exceed 14 ft (168 in). Oversize movements are permitted under Idaho Code 49-1004. ⚠️ Idaho's ESCORT requirements are route-map driven rather than numeric — see the escort section.
Official source for this height limit →
Idaho Code 49-1010(3)(b): the 53 ft semitrailer applies ONLY on the National Network, access routes, and board-approved state highways. Everywhere else the limit is 48 ft. Publishing a flat 53 would put an illegal trailer on a large share of Idaho roads. No general overall limit; 65 ft overall applies on board-designated restricted routes.
Escort / Pilot Car Thresholds (see glossary for terms, certification requirements for the driver)
These escort figures are route-dependent — they can change with road classification, lane width, two-lane vs multilane, and time of day. Confirm with the permit office before dispatching.
- Front escort required over
- 12ft wide
- Rear escort required over
- 12ft wide
- Both escorts required over
- 14ft wide
- Height escort required over
- 16ft tall
Idaho does NOT set fixed numeric width thresholds for escorts. Escort requirements are determined by the ITD 'Pilot/Escort Vehicle Travel and Vertical Clearance of Structures Map' (color-coded routes) and stated on the permit (IDAPA 39.03.05 Sec. 24.3). Rule-based triggers that ARE defined: (1) FRONT escort with a non-metallic HEIGHT POLE for all loads over 16 ft (192 in) high; front escort otherwise required where the load cannot stay in its lane. (2) REAR escort when load width blocks rearward view so the driver cannot see 200 ft behind (a visibility test, not a fixed width). (3) A THIRD/ADVANCE escort may be required to hold opposing traffic at turnouts. (4) POLICE/AMBULANCE escort plus ISP inspection on US-12 through the Nez Perce-Clearwater Forest (MP 74-174) for loads over 16 ft wide, over 150,000 lbs, and/or over 150 ft long. Extra ITD approval (up to 24 working hrs) required over 16 ft wide (red/black routes), 18 ft wide (interstate), 16 ft high, 120 ft long (non-interstate), or 150 ft long (interstate).
Travel Restrictions
- Night travel
- Generally allowed
- Weekend travel
- Generally allowed
- Sunday travel
- Generally allowed
Travel rules depend on route color-coding on the ITD Pilot/Escort & Vertical Clearance Map. BLACK routes and INTERSTATE: loads not over 12 ft wide, 120 ft long, 15 ft high may travel 24/7; larger loads follow map restrictions. RED routes: DAYLIGHT only, travel only until 2:00 p.m. Friday or the day before a holiday, and NO Saturday/Sunday travel. Loads traveling 30 min after sunset to 30 min before sunrise (or visibility <500 ft) need extra lighting. HEAVY COMMUTER: loads over 13 ft wide prohibited on state roadways 6:00-9:00 a.m. and 4:00-6:30 p.m. Mon-Fri in listed metro corridors (Boise, Coeur d'Alene, Idaho Falls, Pocatello, Twin Falls). Movement invalid in hazardous conditions (ice/snow, wind over 40 mph, visibility under 500 ft). Booleans reflect that night/weekend/Sunday travel IS permitted for compact loads on black/interstate routes but PROHIBITED on red routes - always check the permit and route map.
Holiday blackouts: Designated holidays with restricted travel (oversize movement generally stops before the holiday, resumes sunrise the day after): New Year's Day, Memorial Day, Independence Day, Labor Day, Thanksgiving, and Christmas. On black routes over-dimension loads limited to travel before 4:00 p.m. the day before a holiday; on red routes travel stops at 2:00 p.m. the day before.
Extreme-Load Escalation Triggers
This jurisdiction does not define a "superload" class. The figures below are triggers for other escalations — read the note beneath them before planning against these numbers.
- Width over
- 17ft
- Length over
- 150ft
- Weight over
- 200,000 lbs
Idaho does NOT define a formal 'superload' category with fixed thresholds. Escalating extreme-load tiers: licensed-engineer/ATSSA traffic control plan required on 2-lane highways when width >18 ft, length >150 ft, or height >16 ft; additional ITD approval over 16 ft wide (red/black), 18 ft wide (interstate), 16 ft high; BRIDGE ANALYSIS when single/steer axle exceeds 35,000 lbs (up to 3 business days to 250,000 lbs, up to 10 days over; over 800,000 lbs requires third-party analysis); US-12 (MP 74-174) loads over 16 ft wide/150,000 lbs/150 ft long trigger USFS review plus ambulance/law-enforcement escort.
Estimated Permit Cost Verify before relying
Per-mile road-use formula (4¢–$1.02+/mile by weight/axle bracket) confirmed in statute; the commonly-cited flat $33 admin fee could NOT be confirmed at a primary source
Source: Idaho statute (road-use formula only) — verify current fee with the permit office before budgeting a move.
Permit fee only — does not include escort/pilot-car service costs (market-rate, arranged separately) or third-party permit-service fees. This is an estimate for planning purposes, not a quote.
Get a Permit
- Online portal
- https://permits4idaho.com/
- Phone
- 208-872-3163
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