Illinois

Illinois interstate GVW limit: 80,000 lbs. Per-axle limits: Single axle 20,000 lbs, Tandem axle 34,000 lbs, Tridem axle 42,000 lbs. Federal bridge formula applies. Enforcement tolerance: 2% tolerance on axle weights at weigh stations.

Height: 14 ft. Width: 8 ft 6 in. Trailer length: 53 ft (semitrailer). Overall combination length: 65 ft combination (non-designated); no limit on designated network.

Oversize/overweight permits through IDOT online permit system. 2025 law (signed Nov 2025): vehicles powered wholly or partially by natural gas, electric batteries, or hydrogen fuel cells receive a 2,000 lb weight allowance above standard limits Fees: Single-trip: $20+; Annual: $100+. District of Columbia oversize permits are not directly honored in Illinois. You will need to obtain a Illinois-specific permit for oversize/overweight loads. Apply online: https://idot.illinois.gov/transportation-system/transportation-management/permits Enforcement: Weigh stations; roving enforcement; fines based on overweight percentage per axle.

Agricultural: Farm vehicles exempt on non-interstate roads; agricultural implements allowed up to 15 ft wide on local roads.

Spring load limit postings on designated roads; reduced weights during thaw. Check with the state DOT for current postings and dates before planning your route.

For the most current weight and size regulations, permit applications, and seasonal restriction updates, visit the official Illinois DOT page at https://idot.illinois.gov/transportation-system/transportation-management/permits. Contact the Illinois Department of Transportation for specific routing questions.