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Michigan Oversize Permits Information


Michigan Oversize Permits are valid for 5 days. Driver must have a permit prior to entering the state.

Operating Time

Travel is allowed one-half hour before sunrise to one-half hour after sunset, Monday through Friday. Weekend travel is now being permitted on a trial basis for loads not exceeding 10′ wide, 14′ in height, and 90′ in length. No weekend travel when dimensions are greater. However, overweight only with all dimensions, all legal and not exceeding 70′ overall length can have continuous travel.


No travel starting at noon the day preceding a major holiday and holiday weekends until daylight of the first day after the holiday or holiday weekend. Loads over 12′ wide or 90′ long are not to move from 7:00 a.m. – 9:00 a.m. and from 3:00 p.m. – 6:00 p.m. in the following counties: Genesee, Ingham, Jackson, Kalamazoo, Kent, Muskegon, Macomb, Oakland, Saginaw, Westenau, Wayne.

Note on Bridge Crossings: Contact Mackinaw Bridge Authority (phone 906-643-7600) 24 hours prior to planned bridge arrival/crossing. Escort will be provided (no charge) for loads exceeding legal weight or 10′ wide. Crossing is not allowed when winds exceed 25 miles per hour.

Ambassador Bridge (between Detroit and Windsor, Ontario) is now charging $50.00 or more for O/D shipments and may require a one-day notice. They have restricted crossing hours from 10:00 AM to 4:00 PM, Monday through Friday. Ambassador Bridge phone is 313-496-1111.

LIFT AXLES: According to Michigan provision sheet, “Vehicles must have air or lift axles on the ground.” According to the permit office, when under a load, all axles including flip axles must be on the ground if you are overweight.

SEASONAL LOAD RESTRICTIONS: Usually February to April, maximum weights per axle and specific routing may vary. No overweight permits will be issued during the spring weight restriction period. Maximum axle weights may be reduced up to 35%. A tandem group may be allowed only 26,000 pounds (13,000 pounds per axle), or with two tandem groups, they may allow 26,000 pounds for one group and 32,000 for the other tandem group. Frost Phone: 800-787-8960

Speed Limit

Maximum posted limits unless otherwise specified on permit.

Legal Dimensions

The vehicle must have the following characteristics:

  • Width: 8’6″ designated highways, 8’0″ all other roads
  • Height: 13’6″
  • Length: 53′ semi-trailer on Interstate and designated highways, 50′ maximum on non-designated highways. 53’ trailer must have kingpin setting of 41’.
  • Overhang: 3′ front; any rear amount is permissible if the legal length is not exceeded.
  • Weight: 80,000 Gross; Steer Axle – 700 pounds per inch of tire width (15,400 pounds with 11″ tires); Tandem – 34,000 (32,000 on non-designated roads, and 26,000 on second tandem); Tridem – 42,000 (39,000 on non-designated); Single – 20,000 designated highways (18,000 other roads)

Routine Michigan Oversize Permit Limits

  • Width: 16′ (or 14′ during spring thaw restrictions)
  • Height: 15′ Shipper/driver are responsible for finding safe routes when the height exceeds 13’6″
  • Length: 150′
  • Weight: “Handled on a case-by-case basis.” Air or lift axles should be on the ground.

You must be registered for at least the amount of weight you are permitting for Michigan.

Loads exceeding these dimensions must be applied for as superloads, and may take up to ten days to issue once shipper letter, route surveys, etc. are received.


  • Width: Over 12′ – 1 escort pilot car; over 14′ – 2 escort pilot cars
  • Height: Over 14’5″ – 1 escort pilot car with high pole; over 15′ – 2 escort pilot cars and a route survey must be submitted and approved.
  • Length: Over 90′ – 1 escort pilot car; over 100′ – 2 escort pilot cars. Overhang: Over 15′ – 1 escort pilot car.

Security Measures

“Oversize Load” signs are required on the front of the vehicle and on the rear of the load for any over dimensional load. An over width or over length vehicle/load requires flags at each corner of the load, with an additional flag at the widest point on each side of the load if it extends beyond the corner flags. When rear overhang is 4′ or more, the extreme rear of the load must have a flag for daytime running, and a red light or lant

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