Overview
Montana oversize and overweight permits are issued by the Montana Department of Transportation, Motor Carrier Services Division. Single-trip permits are valid for three consecutive days.
Permit approval depends on the proposed route, dimensions, axle weights and infrastructure conditions.
Permit Office
| Office | Montana Department of Transportation, Motor Carrier Services Division |
| Address | 2550 Prospect Avenue, Helena, Montana 59601 |
| Contact | (406) 444-7262 |
| Hours | 8:00 A.M. – 5:00 P.M. (MT) |
Permit Basics
| Permit validity | Single-trip permits are valid for three (3) consecutive days. |
| Operating time | 8:00 A.M. – 5:00 P.M. (MT) |
Dimensions & Weights
Routine permit limits
| Length | 150′ |
| Width | 18′ |
| Height | 17′ |
| Axle / group | Spacing | Weight |
|---|---|---|
| Single | — | 20,000 |
| Tandem | — | 48,000 |
| Tridum | — | 51,750 |
| Quad | — | 55,440 |
Escort Requirements
| Based on | Escorts required |
|---|---|
| Width | On interstate — width over 16′6″: 1 rear |
| Width | On 2-lane or multi-lane non-interstate — width over 12′6″ up to 14′: 1 front |
| Width | On 2-lane or multi-lane non-interstate — main body over 14′ or overall width over 15′: 2 (front & rear) |
| Width | On non-interstate only (load not over 16′ wide or 120′ long) — width over 10′ and not equipped with required lights/signs: 2 (front & rear) |
| Length | On interstate — length over 120′: 1 rear |
| Length | On 2-lane or multi-lane non-interstate — length over 110′: 1 rear |
| Height | Height over 17′ (before permit application): route survey required |
- Convoys — no more than 5 O/O loads needing escorts may convoy if width not over 14′ (or 15′ with projections) and not over 120′ long: 2 (front & rear)
- Convoys — no more than 5 vehicles needing escorts may convoy if any unit is over-length on 2-lane highways or over 110′ on interstate highways: 2 (front & rear)
- Convoy escort must display sign: ‘Oversize Load, Convoy Follows (# of vehicles).’
Notes
- Gross Weight — 5 Axles: 107,000
- Gross Weight — 6 Axles: 110,000
- Gross Weight — 7 Axles: 114,000
- Gross Weight — 8 Axles: 126,000