Missouri Truck Weight Limits

How much a truck can weigh in Missouri

Missouri runs on the federal numbers: 80,000 lb gross, 20,000 on a single axle, 34,000 on a tandem (RSMo 304.180). Off the interstate you can go 2,000 lb over the axle limits, and milk and livestock haulers get 85,500 lb. Fines start small and scale, 2 cents a pound for the first 500 over, 5 cents for the next 500, then 10 cents a pound past 1,000 over (RSMo 304.240).

Axles, off-Interstate, and permits

• Off the Interstate: 80,000 lb; 85,500 lb for milk and livestock haulers off the interstate, and non-interstate axles may run 2,000 lb over the standard limits (RSMo 304.180)
• Single axle: 20,000 lb; up to 22,000 lb off the interstate (2,000 lb allowance)
• Tandem axle: 34,000 lb; up to 36,000 lb off the interstate
• With a permit: 109,600 lb for a local log truck and 85,500 lb for milk/livestock off the interstate (RSMo 304.180); anything heavier moves on a single-trip superload permit. No grandfathered LCV tier.
• Standard 5-axle semi tops out at 80,000 lb everywhere. The higher figures are commodity-specific statutory allowances, not routine permits.

Posted bridge and road limits

County and city bridges get posted 'WEIGHT LIMIT X TONS' signs, and tons means short tons of 2,000 lb, so 10 tons is 20,000 lb. A posted limit beats the legal max: if a bridge is posted under your gross you can't cross even at a legal 80,000, and you detour. Crossing a posted bridge over its rating is its own violation, and you can be billed for any structural damage on top of the fine.

What running heavy costs

Per-pound scale under RSMo 304.240: 2 cents a pound for the first 500 lb over, 5 cents a pound for the next 500 (501-1,000), then 10 cents a pound for everything past 1,000 over, with a $5 minimum. Example: 5,000 lb over runs about $435. Local log trucks get a separate 10/20/50-cent scale.

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