Missouri Weigh Stations & Ag Inspection

When Missouri makes you pull in

Only trucks licensed over 18,000 lb GVW must pull into an open Missouri scale (RSMo 304.235); lighter rigs stop only when an officer waves them in. On the road, the lit OPEN sign is your order, and a loaded 40,000-lb truck can't skip it. Evade and get caught out of compliance and you face the general Chapter 304 penalty: up to $500 and up to a year in county jail (RSMo 304.570).

Stations, bypass, and inspection

• Who must stop: Over a weight threshold
• Where the stations are: Main fixed scales sit on the I-70 (Kingdom City, Foristell), I-44, and I-55 (Bloomsdale) corridors, with sites on I-29, I-35, and US routes. Hours vary; lit OPEN/CLOSED signs and ramp signals tell you whether to exit. Portable scales and roving Commercial Vehicle Enforcement officers work the gaps between fixed sites.
• Bypass: Both PrePass and Drivewyze operate statewide. PrePass runs transponder and app sites, including Bloomsdale SB on I-55, and HELP Inc. runs weigh-in-motion sensors at several Missouri scales; Drivewyze (app/ELD, no transponder) covers fixed and mobile sites on the I-70, I-44, and I-55 corridors. Green means stay on the mainline at speed; red or no signal means pull in and stop.
• Ag / border inspection: None. Interior state with no agricultural or border produce-inspection stations. A weigh-station bypass subscription covers the scales here; there is no separate quarantine checkpoint to clear.
• Fine for passing an open station: The general Chapter 304 penalty applies to evading a weigh station: a fine of $5 up to $500 and/or up to one year in county jail (RSMo 304.570), a misdemeanor-level penalty, on top of any overweight fine if you are found heavy.

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