Oversize and Overweight Permit Requirements
Standard legal vehicle dimensions and weights define the boundary beyond which a permit is required. Standard dimensions on the U.S. Interstate system (specific limits vary by state): maximum width 8.5 feet (102 inches); maximum height 13.5–14 feet (varies by state — California is 14 feet, most eastern states 13.6 feet); maximum length for a single motor vehicle 40 feet; maximum combination length 65 feet (with many states allowing 70–75 feet under grandfathering provisions); and maximum weight 80,000 lbs GVW under Bridge Formula. Any vehicle or load exceeding any of these dimensions or weights requires an oversize/overweight (OVW) permit — a state-issued authorization specifying the exact load, dimensions, route, travel time windows, and conditions for the move. Permits are state-specific: a permitted load moving through five states requires five separate permits (or use of an authorized permit service that coordinates multi-state permitting). Permitted dimensions that are commonly allowed with a single permit and pilot car requirements: Width 8.5–12 feet — typically requires one or two pilot cars (lead car, and/or chase car depending on width and state); over 16 feet — may require two pilot cars and a law enforcement escort; Height over 14 feet — required vertical clearance surveys of the route; length over 100 feet — may require rear escort. Super-load status (extremely heavy loads, typically over 250,000 lbs) requires engineering analysis of bridge load capacity on the proposed route, often taking weeks to permit. The permit specifies: authorized route only (no deviations without authorization); travel time windows (prohibited during rush hours in metropolitan areas, weekend restrictions in some states, seasonal restrictions on weight during spring thaw when road surfaces are most vulnerable to damage); and flags, signs, and lighting on the load and escort vehicles.