South Dakota commercial vehicle weight limits follow the federal Interstate standard of 105,500 lbs gross, 20,000 lbs per single axle, and 34,000 lbs per tandem axle group. The federal bridge formula (23 U.S.C. 127) applies on all routes. South Dakota imposes spring weight restrictions on secondary roads typically February through April. Many county roads have severe restrictions during spring thaw. Check SDDOT for current restricted routes and weight postings before dispatching on non-Interstate routes during this period. Oversize and overweight permits are available from SD DOT for loads exceeding standard limits. Verify current road-specific postings with the South Dakota DOT before routing heavy loads.
South Dakota imposes spring weight restrictions on secondary roads typically February through April. Many county roads have severe restrictions during spring thaw. Check SDDOT for current restricted routes and weight postings before dispatching on non-Interstate routes during this period.
Check current restrictions at SD DOT →The federal bridge formula limits the weight on any group of axles based on the distance between the outermost axles in the group. It applies in South Dakota on all routes where federal standards apply.
W = maximum weight in lbs · L = axle spacing in feet · N = number of axles
SDDOT issues oversize/overweight permits. Single-trip permits required for loads exceeding standard limits. Annual permits available for qualifying recurring operations including agricultural and energy sector heavy haul. Superloads require engineering review and route approval.
Apply for South Dakota OS/OW Permit →South Dakota allows up to 105,500 lbs gross vehicle weight on designated state primary routes — one of the highest limits in the continental US. This primarily benefits agricultural operators. On Interstate highways, the federal standard of 80,000 lbs applies. Overweight permits from SDDOT are required for loads exceeding applicable limits.
Yes. South Dakota imposes spring weight restrictions on secondary roads and county routes typically from February through April during the spring thaw. These restrictions can be severe on rural county roads. Interstate highways are generally not affected. Check SDDOT at dot.sd.gov for current restricted routes before routing heavy loads on secondary roads during spring.
Vehicles operating at weights above 80,000 lbs on designated state routes need to comply with South Dakota's weight regulations for those routes. Agricultural vehicles with qualifying configurations may be eligible for the higher limits on designated routes, but permit requirements vary by load type and route. Contact SDDOT for specific guidance on agricultural weight allowances.
South Dakota oversize/overweight permits are issued by the SDDOT Permits Office at dot.sd.gov. Single-trip permits are required for most oversize or overweight loads. Annual permits are available for qualifying recurring operations. Superloads require engineering review. The permit system is available online for most standard configurations.
During spring weight restriction season (typically February–April), South Dakota county roads may be posted with dramatically reduced weight limits — sometimes as low as 6 to 10 tons — to protect road infrastructure during the freeze-thaw cycle. These restrictions vary by county and road condition. Always check with SDDOT and the relevant county highway department before routing heavy loads on county roads during spring.
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The information on this page is compiled from publicly available government sources and is provided for general informational purposes only. TruckRadar is an independent search engine — we are not affiliated with any government agency and this content does not constitute legal or compliance advice. Regulations change frequently; always verify current requirements directly with the official source before making compliance decisions.
Official source: South Dakota SD Department of TransportationLast reviewed: 2026-04