South Dakota OS/OD Overview
Permit Required
Yes – any load exceeding legal size or weight must obtain a permit from the South Dakota Department of Transportation (SDDOT).
Legal Limits (Without Permit)
- Width: 8'6"
- Height: 14'
- Length: 75' (combo); 53' trailer allowed
- Weight: 80,000 lbs GVW (with standard axle spacing)
Permitted Load Maximums (Typical Upper Limits)
- Width: Up to 18' with escort
- Height: Over 15'6" requires route survey and utility clearance
- Length: Over 130' requires escort and route approval
- Weight: Over 200,000 lbs with engineering analysis
Superloads require advance application, detailed axle/spacing info, and often bridge review and local coordination.
Travel Hours
- Standard: ½ hour before sunrise to ½ hour after sunset
- Weekend: Allowed for loads under 12' wide and 110' long
- Holidays: No travel on major holidays or after noon the day before
- Night travel: May be allowed for loads under 10' wide with proper lighting and approval
Escort Requirements (General Guidelines)
| Dimension | Escort Requirement |
|---|---|
| Width > 12' | 1 Escort (front on 2-lane, rear on 4-lane) |
| Width > 14' | 2 Escorts (front and rear) |
| Height > 15'6" | High pole escort + utility coordination |
| Length > 130' | 1 or more Escorts as required by route |
Additional Notes
- Loads must display “Oversize Load” signs, red/orange flags, and amber lights as per permit
- Seasonal weight restrictions (frost laws) may apply in spring
- Permits issued through the SDDOT Automated Oversize/Overweight Permitting System
Detailed Information
PERMITS: Permits valid for three days. Must have permit prior to entering the state.
OPERATING TIME: One-half hour before sunrise to one-half hour after sunset, including Saturday and Sunday. Loads not exceeding 10' wide, 14'6" high, 110' overall length may travel on interstate highways continuously and within a 2-mile radius of Interstate Highway interchanges on state highways. Loads that are only overweight may operate 24/7.
LEGAL DIMENSIONS: Width: 8'6'' Height: 14'' Length: 53' semi-trailer, overall length not limited. Overhang: 3' front, 4' rear, or 53' trailer and load. Poles, pipes, beams, utility poles, etc. are not exempt from permits for length or rear overhang. Weight: 80,000 Gross Single – 20,000 Tandem – 34,000 Tridem – 42,000 Steer Axle may not exceed 600 pounds per inch of tire width. Divisible Loads Exceeding 80,000: You can exceed 80,000 gross without a permit on state highways as long as you are legal on all axle/group weights and you are licensed for at least the amount of your gross weight. However, if you need any Interstate route, you will need to get an "Interstate Permit."
ROUTINE PERMIT LIMITS: Width: Depends on routes Height: Depends on routes Length: Depends on routes Weight: Single – 24,000 Tandem – 46,000* Tridem – 60,000* Quad – 68,000* Steer – 600 lbs. per inch of width (13,200 for 11" steers) Register for at least the amount of weight you wish to permit, or pay extra for a trip permit. Some routes will allow more weight. SD will have to determine by route. All axles must be on the ground when permitting for overweight load. Tractor must be registered for weight hauled, or pay an extra fee for the trip with the permit order.
ESCORTS: Width: On Interstate Highways: Over 16' – 1 escort. On most State Highways: Over 20' – 1 escort. Multiple escorts are required if the load extends more than two feet into adjacent driving or passing lanes, or if traffic cannot pass without the permitted vehicle or passing vehicle driving on the shoulder of the road. Black Hills area, except on US16 from Rapid City to Keystone, WY & US 18: over 10' – 1 escort. Length: Over 130' – 1 escort Height: Normally no requirements.
SEASONAL LOAD (WEIGHT) RESTRICTIONS: Spring thaw load weight restrictions may go into effect anytime after February 15th. Check with Permit Office.
SIGNS, FLAGS & LIGHTS: All overdimensional vehicles and loads must display flags. Flags must be attached to all corners of vehicles or loads wider than 8'6'' and to corners of any load extending beyond the width of the hauling vehicle. Flags are also to be attached to load projections exceeding 3 feet in front of the vehicles front bumper, or more than 4 feet beyond the rear of the trailer. If the front or rear projection is not wider than two feet, at least one flag is needed on the projection, and 2 flags are required on the projection if it is over 2 feet in width.
“Oversize Load” or “Oversized Load” signs are required front and rear on all permit vehicles that exceed a width of 12 feet or a length of 95 feet, or that operate during nighttime hours. Signs must be reflectorized when used for night moves.
Signs must be covered or removed when they are not required.
Load projections must be lighted for nighttime running with amber lights, red lights, and reflectors. The specific
requirements of nighttime lighting are listed on the South Dakota permit.