Legal size limits without a permit
| Measurement | Michigan legal limit |
|---|---|
| Height | 13'6" |
| Width | 8'0" (96 in) on non-designated highways; 8'6" (102 in) on designated highways |
| Front Overhang | 3 ft |
| Rear Overhang | Permitted if legal overall length isn't exceeded; requires a red flag/light if 4+ feet |
Axle and gross weights
How much each axle group and the whole vehicle can carry in Michigan, without a permit and with an overweight permit.
| Axle group | Legal limit | With a permit |
|---|---|---|
| Steer axle | Confirmed at filing | Confirmed at filing |
| Single axle | 18,000 lbs (9+ ft spacing) | Wheel-load based: 700 lbs per inch of tire tread width |
| Tandem axle | 34,000 lbs (9+ ft spacing) | Per axle-group configuration/bridge formula; extended permits allow 24,000 lbs per axle |
| Tridem axle | Confirmed at filing | Confirmed at filing |
| Quad axle | Confirmed at filing | Confirmed at filing |
| Gross weight | 80,000 lbs, subject to the Bridge Gross Weight Formula | 150,000 lbs under Construction Equipment and Annual Miscellaneous extended permits |
Superload: Loads exceeding single-trip limits of 16 ft wide, 15 ft high, or 150 ft long are treated as superloads
Permit types we file in Michigan
Single-Trip PermitValid for one trip; typically issued for a five-day period, up to 150'/16'/15'.
Extended (Annual) PermitIssued annually by vehicle/load category — construction, miscellaneous, agricultural, or modular/mobile home.
Category-Specific PermitsConstruction equipment, shipping containers, raw forest products, and hydraulic boat lift permits.
Maximum dimensions with a permit
| Dimension | Maximum with a permit |
|---|---|
| Length | 150 ft (single-trip permit ceiling); 85 ft (extended/annual permit ceiling) |
| Width | 16 ft (single-trip); 12'6" (extended/annual) |
| Height | 15 ft (single-trip); 14 ft (extended/annual) |
| Rear Overhang | Confirmed at filing |
Loads beyond the single-trip ceiling of 150 ft long / 16 ft wide / 15 ft high are classified as superloads requiring written justification and advance route certification.
Escorts and travel restrictions
Escort & pilot car rules
- One rear escort vehicle with a flashing amber light and 'OVERSIZE LOAD' sign required for qualifying oversize loads.
- One front escort with a fixed height-measuring device required when height exceeds 14'6".
When you can travel
- Daylight hours only, Monday through Friday, for most oversize permits.
- No weekend or holiday movement permitted under standard oversize permits.
- Rush-hour restriction (7-9 a.m. and 3-6 p.m.) in 11 specified counties including Wayne, Oakland, and Macomb.
- Permits are not valid when wind velocity exceeds 25 mph.
Signs, flags and lights
Most states require
- An “OVERSIZE LOAD” banner on the front of the truck and the rear of the load.
- Red or fluorescent orange warning flags at each corner and at the widest points of the load.
- Amber warning lights or clearance lights when moving at night, where night travel is allowed.
Michigan specifics
- Banner size, flag size and light rules for Michigan are listed on your permit.
- We include them in your permit notes so your driver has them before the trip.
Rules change. Limits and requirements are set by MDOT and can change. We confirm the current rules for your exact load before filing.