South Dakota Truck Weight Limits

How much a truck can weigh in South Dakota

South Dakota is a 129,000-pound state. With an LCV permit an eight- or nine-axle combination runs up to 129,000 on the Interstate and designated state routes (SDCL ch. 32-22), still capped at 20,000 on a single axle and 34,000 on a tandem. Without the permit you are at the federal 80,000. The annual over-80,000 Interstate permit is $60; single-trip is $25.

Axles, off-Interstate, and permits

• Off the Interstate: 80,000 lb base; up to 129,000 lb on designated routes with an LCV permit
• Single axle: 20,000 lb
• Tandem axle: 34,000 lb (tridem 42,000 lb)
• With a permit: 129,000 lb Longer Combination Vehicle on the Interstate and designated state routes; still 20,000 single / 34,000 tandem, four tires on every axle but the steer (SDCL ch. 32-22)
• The 129,000-lb LCV needs four tires on every axle but the steer, and is held to 65 mph on the Interstate, 55 elsewhere. Tridem axle 42,000. The exact SDCL section numbering for the fine schedule versus the LCV grant is best confirmed against the current code, but the dollar tiers and 129,000 ceiling are firm.

Posted bridge and road limits

County and local road authorities post 'WEIGHT LIMIT __ TONS' on roads and bridges (short tons; a 12-ton sign = 24,000 lb). The posted limit overrides your legal gross, so legal on the highway does not mean legal on a posted bridge. Cross one over the limit and you are stopped and cited, and you can be held liable for structural damage.

What running heavy costs

Per-pound scale on the excess (SDCL 32-22-55): 1,000-3,000 over = 5 cents/lb; 3,001-4,000 = 15 cents/lb; 4,001-5,000 = 22.5 cents/lb; 5,001-10,000 = 37.5 cents/lb; 10,001 and up = 75 cents/lb. Example: 12,000 lb over runs about $9,000. Overweight operation is also a Class 2 misdemeanor (up to $500 or 30 days), and the vehicle is held until made legal.

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