Federal regulations
South Dakota has adopted
Part 392 of the Federal Regulations.
Applicability
Part 392 applies to drivers and motor carriers operating intrastate vehicles and combinations of vehicles with three or more axles or with a gross vehicle weight rating of 26,001 or more pounds, and any size or type of vehicle used to transport hazardous materials requiring placarding.
Speed limit
The speed limit is 80 mph on designated rural interstates, 70 mph on select 4-lane highways, 65 mph on other main highways (or as posted).
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