Legal size limits without a permit
| Measurement | Montana legal limit |
|---|---|
| Height | 14'0" (no permit) |
| Width | 8'6" (no permit) |
| Front Overhang | Confirmed at filing |
| Rear Overhang | Loads may extend to an overall combination length of 75' without a permit |
Axle and gross weights
How much each axle group and the whole vehicle can carry in Montana, 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 | 20,000 lbs | Term Overweight permits allow up to 5,000 lbs excess per axle |
| Tandem axle | 34,000 lbs | Up to 15,000 lbs excess under a Term Overweight permit |
| Tridem axle | Confirmed at filing | Confirmed at filing |
| Quad axle | Confirmed at filing | Confirmed at filing |
| Gross weight | 80,000 lbs | 132,000 lbs under Montana's wintertime weight permit; UNCONFIRMED for general annual permit cap otherwise |
Superload: Class 1 superload: 18'–34' wide, 17'–24' high, and/or 150'–200' long; Class 2: exceeding 34' wide, 24' high, and/or 200' long
Permit types we file in Montana
Single Trip / Temporary Trip PermitValid up to 72 hours for an individual non-divisible oversize/overweight move.
Term/Annual PermitIncludes Term Overweight, Weight Mileage, and commodity-specific annual permits.
Special/Superload PermitClass 1 and Class 2 superload permits for loads exceeding standard term-permit dimensions.
Maximum dimensions with a permit
| Dimension | Maximum with a permit |
|---|---|
| Length | 150' (general term/annual ceiling before Class 1 superload review) |
| Width | 16' (mobile-home annual permit ceiling); 18' generally allowed on Interstates |
| Height | 15'6" (general/annual permit ceiling) |
| Rear Overhang | 15' maximum (raw log loads) |
Montana defines two superload tiers by dimension: Class 1 (2-business-day review) and Class 2 (5-business-day review).
Escorts and travel restrictions
Escort & pilot car rules
- Interstate, width 16'6"–18': one rear pilot vehicle.
- Interstate, width over 18': at least two rear pilot vehicles side-by-side.
- Non-Interstate, width 12'6"–16'6": one front pilot.
When you can travel
- Daylight-only travel required on non-Interstate routes for loads over 10' wide, 150' long, or 15'6" high.
- Weekend travel barred for non-Interstate loads over 18' wide, 150' long, or 17' high.
- Holiday/holiday-weekend ban for oversize loads on major federal holidays.
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.
Montana specifics
- Banner size, flag size and light rules for Montana 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 MDT and can change. We confirm the current rules for your exact load before filing.