Iowa Truck Weight Limits
Complete guide to commercial vehicle weight regulations in Iowa, including axle limits, permit requirements, and seasonal restrictions.
Weight Limits
| Axle Type | Iowa 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 |
Iowa 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.
Iowa 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
Iowa 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 Iowa
| Permissible Gross Loads for Vehicles in Iowa | ||||||||
|---|---|---|---|---|---|---|---|---|
| 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 | 34,000 | — | — | — | — | — | — |
| 9 | 39,000 | 43,000 | — | — | — | — | — | — |
| 10 | 40,000 | 43,500 | — | — | — | — | — | — |
| 11 | 40,000 | 44,500 | — | — | — | — | — | — |
| 12 | 40,000 | 45,000 | 50,000 | — | — | — | — | — |
| 13 | 40,000 | 46,000 | 50,500 | — | — | — | — | — |
| 14 | 40,000 | 46,500 | 51,500 | — | — | — | — | 80,000 |
| 15 | 40,000 | 47,500 | 52,000 | — | — | — | — | 80,000 |
| 16 | 40,000 | 48,000 | 52,500 | 58,000 | — | — | — | 80,000 |
| 17 | 40,000 | 49,000 | 53,500 | 58,500 | — | — | — | 80,000 |
| 18 | 40,000 | 49,500 | 54,000 | 59,500 | — | — | — | 80,000 |
| 19 | 40,000 | 50,500 | 54,500 | 60,000 | — | — | — | 80,000 |
| 20 | 40,000 | 51,000 | 55,500 | 60,500 | 66,000 | — | — | 80,000 |
| 21 | 40,000 | 52,000 | 56,000 | 61,000 | 66,500 | — | — | 80,000 |
| 22 | 40,000 | 52,500 | 56,500 | 62,000 | 67,000 | — | — | 80,000 |
| 23 | 40,000 | 53,500 | 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 | 55,000 | 58,500 | 63,500 | 69,000 | 74,500 | 80,000 | 80,000 |
| 26 | 40,000 | 55,500 | 59,500 | 64,500 | 69,500 | 75,000 | 80,000 | 80,000 |
| 27 | 40,000 | 56,500 | 60,000 | 65,000 | 70,000 | 76,000 | 80,000 | 80,000 |
| 28 | 40,000 | 57,000 | 60,500 | 65,500 | 71,000 | 76,500 | 80,000 | 80,000 |
| 29 | 40,000 | 58,000 | 61,500 | 66,000 | 71,500 | 77,000 | 80,000 | 80,000 |
| 30 | 40,000 | 58,500 | 62,000 | 67,000 | 72,000 | 77,500 | 80,000 | 80,000 |
| 31 | 40,000 | 59,500 | 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 | 61,000 | 64,000 | 68,500 | 74,000 | 79,500 | 80,000 | 80,000 |
| 34 | 40,000 | 61,500 | 64,500 | 69,500 | 74,500 | 80,000 | 80,000 | 80,000 |
| 35 | 40,000 | 62,500 | 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 | 64,000 | 66,500 | 71,000 | 76,000 | 80,000 | 80,000 | 80,000 |
| 38 | 40,000 | 64,500 | 67,500 | 72,000 | 77,000 | 80,000 | 80,000 | 80,000 |
| 39 | 40,000 | 65,500 | 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 | 67,000 | 69,500 | 73,500 | 78,500 | 80,000 | 80,000 | 80,000 |
| 42 | 40,000 | 67,500 | 70,000 | 74,500 | 79,000 | 80,000 | 80,000 | 80,000 |
| 43 | 40,000 | 68,500 | 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 | 70,000 | 72,000 | 76,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 46 | 40,000 | 70,500 | 72,500 | 77,000 | 80,000 | 80,000 | 80,000 | 80,000 |
| 47 | 40,000 | 71,500 | 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 | 73,000 | 74,500 | 78,500 | 80,000 | 80,000 | 80,000 | 80,000 |
| 50 | 40,000 | 73,500 | 75,500 | 79,500 | 80,000 | 80,000 | 80,000 | 80,000 |
| 51 | 40,000 | 74,500 | 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 | 76,000 | 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 | 77,500 | 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 | 79,000 | 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.
Iowa allows a 5% enforcement tolerance on gross weight.
Iowa 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.
Iowa 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 Iowa DOT before making shipping decisions.
Permit Information
Requirements & Costs
- Overweight threshold
- 80,000 lbs
- Single trip permit
- $50
- Annual permit
- $500
- Processing time
- Instant
- Divisible loads
- Not permitted
- Online application
- Available
Required Documents
- Insurance
- Registration
Special Vehicle Provisions
dump Trucks
All-Systems Overweight Permit allows 12% weight overage for dump trucks
construction
10% axle weight increase for material to/from construction sites
permit Weights
All-Systems Overweight Permit ($500/year) allows 5-axle: 89,600 lbs, 6-axle: 100,800 lbs, 7-axle: 107,520 lbs
Contact Information
Permit Office
Hours: Mon-Fri 8:00 AM - 4:30 PM CST
Official Website
Iowa DOT WebsiteImportant Notes
- All-Systems permit not valid on federal interstates (I-80, I-35)
- Construction material hauling permit provides 10% axle weight increase
Calculate Your Weight Compliance
Use our interactive calculator to check if your truck configuration is compliant with Iowa regulations.
Open Weight CalculatorNeighboring States
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Get Expert ConsultationSource: Iowa Code Chapter 321 | Last Updated: 1/15/2025 | Effective: 1/1/2025
Always verify current regulations with official sources before making shipping decisions.