How to read a South Dakota oversize permit
South Dakota oversize and overweight permits come from the Highway Patrol, online through SDAPS or by phone from the SDHP Permit Center, and they must be bought before you enter the state with the load. A permit can be limited to specific loads, roads and time periods, and the state has not published a sample, so read your own permit's route and conditions line by line.
Issued by the South Dakota Highway Patrol, Motor Carrier Services and Permit Center through South Dakota Automated Permitting System (SDAPS). Written from SDHP's published rules; we haven't read a real South Dakota permit yet.
How to read the route
South Dakota has not published a sample permit, so the layout of the route is not known. The Motor Carrier Handbook says a permit may be limited to specific loads, roads and time periods, and is issued only if the route has the clearance and load capacity for your load. State highways are located by Mileage Reference Markers (MRM), small green signs with a number that rise west to east and south to north. On interstates, exit numbers closely match the MRM.
Road names on South Dakota permits
| On the permit | Means |
|---|---|
| I-90 | Interstate 90 |
| US212 | US Highway 212 (South Dakota's lists write US routes with no space or dash) |
| US16A | US Highway 16A, a lettered US route in the Black Hills |
| SD79 | South Dakota Highway 79 |
| MRM | Mileage Reference Marker, the small green number signs along state highways |
Where the route starts and ends
Not published. South Dakota's handbook does not show how a permit writes its start and end points.
Conditions to watch for
No weekend or holiday ban
South Dakota has no weekend or holiday restrictions, but your load size and route may limit you to daylight. Source
“South Dakota does not have weekend or holiday restrictions.”
Daytime moves
Oversize moves are generally daytime only. The state's FAQ names one exception: loads under 10 ft wide that stay on the interstate. Source
“Oversize movements are generally restricted to daytime movement only”
Night on the interstate
Oversize loads on interstates may move at night unless an escort is required, or the load is over 10 ft wide, over 14 ft 6 in high, or over set lengths (single unit over 45 ft, combination over 110 ft). Overweight-only loads may move at night if no escort is needed. Source
“Overweight permit vehicles may move at night provided they do not require an escort.”
Escorts
Escorts are required over 16 ft wide on interstates and over 20 ft wide on other state highways, and when the route or traffic calls for it. The escort runs in front on undivided highways and behind on divided highways. Source
“Escort vehicles must travel in front of the oversize vehicle on undivided highways and behind it on divided highways.”
Flags and signs
Red or orange flags at least 18 by 18 inches go on all oversize loads. OVERSIZE LOAD signs, at least 18 in high by 84 in wide, go front and rear when the load is over 95 ft long, over 12 ft wide, or moving at night. Source
“Red or orange warning flags at least 18” by 18” in size must be displayed on all oversize vehicles or loads.”
Carry the permit
Keep the permit in the truck and show it to any officer who asks. A permit is void if you break its terms or don't fill it out completely. Source
“Permits must be carried in the permitted vehicle and must be presented to any law enforcement official upon demand.”
Easy to miss
- Buy it before the border. All oversize and overweight permits must be purchased before entering South Dakota with the load.
- Sturgis Rally: in Custer, Fall River, Lawrence, Meade and Pennington counties, certain large loads may move only from a half hour before sunrise to 10:00 am, from the Thursday before the first Friday in August through the Sunday after the second Friday.
- Clearances are on you. The state's bridge clearance list is for planning only, leaves out power lines and stop lights, and says the permit holder must verify clearances on the route traveled. The Black Hills tunnels on SD87 and US16A are tight; commercial traffic should not use them as through routes.
Questions
Does South Dakota restrict oversize loads on weekends and holidays?
No. South Dakota has no weekend or holiday restrictions, but depending on size and route you may be limited to daylight hours.
When do I need a pilot car in South Dakota?
When the load is wider than 16 ft on the interstate or wider than 20 ft on other state highways, or when route limits, traffic or an unusual setup call for one.
Can I buy a South Dakota oversize permit after I cross the state line?
No. The Motor Carrier Handbook says all oversize and overweight permits must be purchased before entering the state with the load.
Sources
- SD Motor Carrier Handbook, Chapter 6: Permits
- SD Motor Carrier Handbook, Chapter 6: Commercial & Agricultural Vehicle Permits
- SD Truck Info FAQ: Can I move an oversize load on weekends and holidays?
- SD Truck Info: Clearance & Route Restrictions
- SD Motor Carrier Handbook, Chapter 5: Routes with Special Restrictions
- SDAPS (South Dakota Automated Permitting System)
Your permit is the legal document; follow everything it says. Rules change; check SDHP's site before you move.Last checked October 2026.