Illinois Oversize & Overweight Permits

When Illinois needs a permit

Cross 8'6" wide, 13'6" high or 80,000 lb and Illinois wants an IDOT permit (625 ILCS 5/15-301; 92 Ill. Adm. Code 554). Single-trips start around $12; annuals climb to $1,000 by category. The big trigger is Illinois State Police: mandatory over 18' wide, 18' high or 200' long, billed by the number of ISP troops on your route. Move in daylight and mind Chicago-area rush-hour and weekend limits.

Thresholds, escorts, and curfews

• Legal max before a permit: Permit needed over 8'6" wide, 13'6" high, 80,000 lb gross, or the state legal length limits. Loads within all of those need no permit; over any one, IDOT wants an OS/OW permit before the move.
• Escort / pilot car: Civilian escorts are triggered by width, length and height as set on the permit (escort vehicle GVWR capped at 26,000 lb, driver 18+ and licensed). Illinois State Police escort is mandatory over 18' wide, over 18' high, or over 200' long, billed by the number of ISP troops along the route.
• Superload: Loads beyond IDOT's Table 2 size/weight are treated as superloads, priced on a per-mile formula scaling with weight over 80,000 lb and trip distance, and they need route review. State Police escort attaches over 18' wide, 18' high, or 200' long.
• Travel curfew: Oversize moves are daylight only. Over-dimension loads face Chicago-metro rush-hour and weekend limits. Holiday no-move on the major federal holidays. Read the permit for continuous-travel conditions and the exact metro time windows.
• Permit fee: Single-trip oversize from about $12. Overweight runs on a distance-and-weight formula, and superloads add a bridge/pavement analysis billed by engineering time. Annual permits by category run roughly $200 to $1,000 (top non-divisible OW+OS tier $1,000/yr, $250 for three months).

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