Wisconsin Department of Transportation

Alert: The following services will be unavailable on Saturday, January 5, 2013 from 12 a.m. (midnight) to 6 a.m. CST due to system maintenance.

Permit requirements

Insurance requirements

Carriers are required to have proper amounts of liability insurance and must obtain an oversize/overweight permit before operating.

Lighting requirements

An oversize vehicle, or a vehicle with an oversize load operating during the hours of darkness, shall be equipped with the following additional lamps.

A: for a vehicle with a load which extends beyond the width of the vehicle

  • At the outermost extremity of the foremost edge of the projecting load, an amber lamp visible from the front and side
  • At the outermost extremity of the rearmost edge of the projecting load, a red lamp visible from the rear and side
  • Any portion of an overwidth load extending beyond the width of the foremost or rearmost edge of the vehicle of load shall be marked with an amber lamp visible from the front, both sides, and rear
  • If the overwidth portion of a load measures 3 feet or less from the front to rear, that portion shall be marked with a amber lamp visible from the front, both sides and rear, except that if the overwidth projection is located at or near the rear it shall be marked by a red lamp visible from the front, both sides, and rear 

B: for a vehicle with a load which extends more than 4 feet beyond the rear of the vehicle

  • On each side of the projecting load, one red lamp visible from the side, located so as to indicate maximum overhang
  • On the rear of the projecting load, 2 red lamps, visible from the rear, one at each side; and 2 red reflectors visible from the rear, one at each side, located so as to indicate maximum width

C: All required lamps shall be illuminated whenever a vehicle is operated during the hours of darkness

D: All lamps shall be visible at a distance of 500 feet

Flag requirements

  • Each flag shall be solid red or orange in color, and not less than 18 inches square
  • Flags shall be securely fastened by at least one corner or securely mounted on a staff
  • When a vehicle, load, or vehicle and load is overwidth, a flag shall be fastened at each front and rear corner of the load. In addition, if any part of the load is more than 4 inches wider than the width of load or vehicle at the front or rear, than a flag shall be placed at the widest point of the load
  • When a vehicle, load, or vehicle and load is overlength, a single flag shall be fastened at the extreme rear of the load if the overlength or projecting portion is 2 feet wide or less
  • When a vehicle, load, or vehicle and load is overlength 2 flags shall be fastened at the rear of the load to indicate maximum width if the overlength or projecting portion is wider than 2 feet

Sign requirements

  • When a vehicle, load, or vehicle and load is more than 10 feet wide or is overlength, 2 warning signs shall be displayed. One sign shall be fastened at the front of the power unit and the other at either the rear of the towed unit or at the rear of the load.
  • Each sign shall state, in black letters on a yellow background “OVERSIZE LOAD” and may not be less than 7 feet long and 18 inches high. The letters of the sign may not be less than 10 inches high with a brush stroke of not less than 1.4 inches.
  • The sign message may not be displayed when the vehicle is not operating under a permit.

Warning lamps

When required by a permit, warning lamps shall be operated as follows:

  • All amber flashing or revolving warning lamps shall have a reflector at least 6 inches in diameter and shall be bright enough to be clearly visible and attention-attracting at a distance of 500 feet under all conditions when the load is on the highway, except when visibility is obstructed by a hillcrest, a curve, or an object such as another vehicle 
  • All warning lamps shall flash at a rate of 30 to 90 times per minute
  • Strobe lamps may be used in lieu of flashing or revolving lamps
  • Warning lamps may not be operated when a vehicle is not operating under a permit


Example of additional markings and identifiers

If you have questions:

  • Email: oversize-permits.dmv@dot.wi.gov
  • Call: (608) 266-7320
  • FAX: (608) 264-7751
  • Write to the address below:

    Wisconsin Department of Transportation
    Motor Carrier Services
    PO Box 7980
    Madison, WI 53707-7980

Questions about the content of this page:
Motor Carrier Services, oversize-permits.dmv@dot.wi.gov
Last modified: December 10, 2013

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