Idaho Truck Weight Limits
Complete guide to commercial vehicle weight regulations in Idaho, including axle limits, permit requirements, and seasonal restrictions.
Weight Limits
| Axle Type | Idaho Limit | Federal Limit | Difference |
|---|---|---|---|
| Single Axle | 20,000 lbs | 20,000 lbs | 0 lbs |
| Tandem Axle | 34,000 lbs | 34,000 lbs | 0 lbs |
| Gross Vehicle Weight | 80,000 lbs | 80,000 lbs | 0 lbs |
| Steer Axle (min) | 12,000 lbs | 12,000 lbs | 0 lbs |
| Steer Axle (max) | 20,000 lbs | 20,000 lbs | 0 lbs |
Idaho has source-verified table, spacing, route, permit, or vehicle-specific rules. The calculator applies verified base limits and implemented contexts, but exact special-case output still needs source-chart fixtures.
Idaho has route-specific weight limits. Default calculation uses interstate/standard operation; select a route context for higher state-route limits.
Showing interstate route, standard operation.
Enforcement tolerance: 5% on gross weight.
Bridge Formula
Idaho uses the standard Federal Bridge Formula to calculate maximum weight on groups of consecutive axles.
- W = Maximum weight (lbs)
- L = Distance between outer axles (ft)
- N = Number of axles in the group
Permissible Gross Loads in Idaho
| Permissible Gross Loads for Vehicles in Idaho | ||||||||
|---|---|---|---|---|---|---|---|---|
| Based on FederalBridge Formula: W = 500 × [LN/(N-1) + 12N + 36] | ||||||||
| Showing interstate route, standard operation | ||||||||
Distance (ft) L | 2 AXLES | 3 AXLES | 4 AXLES | 5 AXLES | 6 AXLES | 7 AXLES | 8 AXLES | 9 AXLES |
| 4 | 34,000 | — | — | — | — | — | — | — |
| 5 | 34,000 | — | — | — | — | — | — | — |
| 6 | 34,000 | — | — | — | — | — | — | — |
| 7 | 34,000 | — | — | — | — | — | — | — |
| 8 | 34,000 | 42,000 | — | — | — | — | — | — |
| 9 | 39,000 | 42,500 | — | — | — | — | — | — |
| 10 | 40,000 | 43,500 | — | — | — | — | — | — |
| 11 | 40,000 | 44,000 | — | — | — | — | — | — |
| 12 | 40,000 | 45,000 | 50,000 | — | — | — | — | — |
| 13 | 40,000 | 45,500 | 50,500 | — | — | — | — | — |
| 14 | 40,000 | 46,500 | 51,500 | — | — | — | — | 80,000 |
| 15 | 40,000 | 47,000 | 52,000 | — | — | — | — | 80,000 |
| 16 | 40,000 | 48,000 | 52,500 | 58,000 | — | — | — | 80,000 |
| 17 | 40,000 | 48,500 | 53,500 | 58,500 | — | — | — | 80,000 |
| 18 | 40,000 | 49,500 | 54,000 | 59,000 | — | — | — | 80,000 |
| 19 | 40,000 | 50,000 | 54,500 | 60,000 | — | — | — | 80,000 |
| 20 | 40,000 | 51,000 | 55,500 | 60,500 | 66,000 | — | — | 80,000 |
| 21 | 40,000 | 51,500 | 56,000 | 61,000 | 66,500 | — | — | 80,000 |
| 22 | 40,000 | 52,500 | 56,500 | 61,500 | 67,000 | — | — | 80,000 |
| 23 | 40,000 | 53,000 | 57,500 | 62,500 | 68,000 | — | — | 80,000 |
| 24 | 40,000 | 54,000 | 58,000 | 63,000 | 68,500 | 74,000 | — | 80,000 |
| 25 | 40,000 | 54,500 | 58,500 | 63,500 | 69,000 | 74,500 | 80,000 | 80,000 |
| 26 | 40,000 | 55,500 | 59,500 | 64,000 | 69,500 | 75,000 | 80,000 | 80,000 |
| 27 | 40,000 | 56,000 | 60,000 | 65,000 | 70,000 | 75,500 | 80,000 | 80,000 |
| 28 | 40,000 | 57,000 | 60,500 | 65,500 | 71,000 | 76,500 | 80,000 | 80,000 |
| 29 | 40,000 | 57,500 | 61,500 | 66,000 | 71,500 | 77,000 | 80,000 | 80,000 |
| 30 | 40,000 | 58,500 | 62,000 | 66,500 | 72,000 | 77,500 | 80,000 | 80,000 |
| 31 | 40,000 | 59,000 | 62,500 | 67,500 | 72,500 | 78,000 | 80,000 | 80,000 |
| 32 | 40,000 | 60,000 | 63,500 | 68,000 | 73,000 | 78,500 | 80,000 | 80,000 |
| 33 | 40,000 | 60,500 | 64,000 | 68,500 | 74,000 | 79,000 | 80,000 | 80,000 |
| 34 | 40,000 | 61,500 | 64,500 | 69,000 | 74,500 | 80,000 | 80,000 | 80,000 |
| 35 | 40,000 | 62,000 | 65,500 | 70,000 | 75,000 | 80,000 | 80,000 | 80,000 |
| 36 | 40,000 | 63,000 | 66,000 | 70,500 | 75,500 | 80,000 | 80,000 | 80,000 |
| 37 | 40,000 | 63,500 | 66,500 | 71,000 | 76,000 | 80,000 | 80,000 | 80,000 |
| 38 | 40,000 | 64,500 | 67,500 | 71,500 | 77,000 | 80,000 | 80,000 | 80,000 |
| 39 | 40,000 | 65,000 | 68,000 | 72,500 | 77,500 | 80,000 | 80,000 | 80,000 |
| 40 | 40,000 | 66,000 | 68,500 | 73,000 | 78,000 | 80,000 | 80,000 | 80,000 |
| 41 | 40,000 | 66,500 | 69,500 | 73,500 | 78,500 | 80,000 | 80,000 | 80,000 |
| 42 | 40,000 | 67,500 | 70,000 | 74,000 | 79,000 | 80,000 | 80,000 | 80,000 |
| 43 | 40,000 | 68,000 | 70,500 | 75,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 44 | 40,000 | 69,000 | 71,500 | 75,500 | 80,000 | 80,000 | 80,000 | 80,000 |
| 45 | 40,000 | 69,500 | 72,000 | 76,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 46 | 40,000 | 70,500 | 72,500 | 76,500 | 80,000 | 80,000 | 80,000 | 80,000 |
| 47 | 40,000 | 71,000 | 73,500 | 77,500 | 80,000 | 80,000 | 80,000 | 80,000 |
| 48 | 40,000 | 72,000 | 74,000 | 78,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 49 | 40,000 | 72,500 | 74,500 | 78,500 | 80,000 | 80,000 | 80,000 | 80,000 |
| 50 | 40,000 | 73,500 | 75,500 | 79,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 51 | 40,000 | 74,000 | 76,000 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 52 | 40,000 | 75,000 | 76,500 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 53 | 40,000 | 75,500 | 77,500 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 54 | 40,000 | 76,500 | 78,000 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 55 | 40,000 | 77,000 | 78,500 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 56 | 40,000 | 78,000 | 79,500 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 57 | 40,000 | 78,500 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 58 | 40,000 | 79,500 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 59 | 40,000 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 60 | 40,000 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 | 80,000 |
Values reflect FHWA policy of rounding down when calculated weights fall exactly halfway between 500-pound increments.
Idaho GVW limit of 80,000 lbs differs from the federal interstate limit of 80,000 lbs.
Idaho allows a 5% enforcement tolerance on gross weight.
Idaho has source-verified table, spacing, route, permit, or vehicle-specific rules. The calculator applies verified base limits and implemented contexts, but exact special-case output still needs source-chart fixtures.
Idaho has route-specific weight limits. Default calculation uses interstate/standard operation; select a route context for higher state-route limits.
Always verify current regulations with Idaho DOT before making shipping decisions.
Seasonal Weight Restrictions
Spring Restrictions
20% weight reduction on secondary
Exemptions: emergency
Permit Information
Requirements & Costs
- Overweight threshold
- 105,500 lbs
- Single trip permit
- $50
- Annual permit
- $800
- Max permit weight
- 200,000 lbs
- Processing time
- Instant online for standard permits
- Divisible loads
- Permitted
- Online application
- Available
Required Documents
- Insurance
- Registration
Special Vehicle Provisions
waste Trucks
Refuse/sanitation trucks operated by city/county/state or agent: +2,000 lbs on all limits (not on interstate)
Single Axle: 22,000 lbs
Tandem Axle: 36,000 lbs
GVW: 82,000 lbs
route Classifications
Color-coded permit routes with increasing weight allowances
tire Requirements
Tire load limits apply to permitted overweight loads
Contact Information
Permit Office
Hours: Mon-Fri 8:00 AM - 5:00 PM MST
Official Website
Idaho DOT WebsiteImportant Notes
- Idaho allows whichever is greater: Federal Bridge Formula or state weight tables
- Refuse/sanitation trucks: +2,000 lbs on all limits (not on interstate)
- Color-coded permit routes: Yellow through Black with increasing weight allowances
- Maximum tire loading: 800 lbs per inch width for permits
- Annual permits limited to 200,000 lbs; heavier loads require single trip permits
- 7-axle dump trucks: up to 84,000 lbs on certain interstate sections
Calculate Your Weight Compliance
Use our interactive calculator to check if your truck configuration is compliant with Idaho regulations.
Open Weight CalculatorNeighboring States
Need Help With Idaho Compliance?
Our experts can help you maximize payload while staying compliant.
Get Expert ConsultationSource: Idaho Code Title 49, Idaho Administrative Code IDAPA 39.03.01 | Last Updated: 1/13/2025 | Effective: 1/1/2025
Always verify current regulations with official sources before making shipping decisions.