Illinois Truck Weight Limits
Complete guide to commercial vehicle weight regulations in Illinois, including axle limits, permit requirements, and seasonal restrictions.
Weight Limits
| Axle Type | Illinois 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 |
Illinois 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.
Showing interstate route, standard operation.
Enforcement tolerance: 5% on gross weight.
Bridge Formula
Illinois 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 Illinois
| Permissible Gross Loads for Vehicles in Illinois | ||||||||
|---|---|---|---|---|---|---|---|---|
| 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.
Illinois allows a 5% enforcement tolerance on gross weight.
Illinois 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.
Always verify current regulations with Illinois DOT before making shipping decisions.
Permit Information
Requirements & Costs
- Overweight threshold
- 80,000 lbs
- Single trip permit
- $75
- Annual permit
- $750
- Processing time
- Instant via ITAP system
- Divisible loads
- Not permitted
- Online application
- Available
Required Documents
- Insurance
- Registration
Special Vehicle Provisions
special Haul Vehicles
Special Haul Vehicle (SHV) exemption for 3-axle concrete mixers on non-interstate roads
Single Axle: 22,000 lbs
Tandem Axle: 40,000 lbs
GVW: 54,000 lbs
dump Trucks
Illinois dump truck limits on non-interstate highways. Straight trucks limited to 4 axles. 4-axle dumps: up to 66,000 lbs with proper configuration.
federal Bridge Formula
Federal Bridge Formula applied statewide. Straight trucks limited to maximum 4 axles.
construction
Construction vehicles may qualify for excess weight permits on designated routes. Contact IDOT for route-specific permits.
Contact Information
Permit Office
Hours: Mon-Fri 8:00 AM - 5:00 PM CST
Official Website
Illinois DOT WebsiteImportant Notes
- STANDARD LEGAL LIMIT: 80,000 lbs gross weight, federal axle limits (no permit required)
- Special Haul Vehicle exemption: 3-axle concrete mixers up to 54,000 lbs (not on interstates)
- Illinois Transportation Automated Permit (ITAP) system provides instant permits
- Federal Bridge Formula applied statewide, straight trucks limited to 4 axles
- Local jurisdiction permits required for non-state roads
Calculate Your Weight Compliance
Use our interactive calculator to check if your truck configuration is compliant with Illinois regulations.
Open Weight CalculatorNeighboring States
Need Help With Illinois Compliance?
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Get Expert ConsultationSource: Illinois Vehicle Code Chapter 625, IDOT Size & Weight Regulations | Last Updated: 1/13/2025 | Effective: 1/1/2025
Always verify current regulations with official sources before making shipping decisions.