ALL commercially registered vehicles are required by CA law to stop at an open scale or roadside inspection, (when the DOT pick-up guy has his rag-sign out). This means a Mazda B-2000 p/u with comm. plates is required by law to stop at scales.
This is why you see "no pick-ups" signs at scale entrances especially on main routes, (5, 80, 15, etc. ).
By CA law a vehicle can no longer be a "pick-up" once the GVWR is over 11,500. For example, all new Ford F-450's even with a factory p/u bed are Motortrucks by CA law not pick-ups.
ALL motortrucks over 10,000 GVWR must have CA motor carrier permit, (MCP), (goes w/ CA#) or have US DOT registration and non-expiring MCP.
Many CA DOT scale workers are unaware of the above and thus when gramps pulls into the scale in his f-450, OR Freightliner conversion, flying his proper DOT or CA# he gets hollered at for following the law.
If you operate a motortruck over 10,000 GVWR over 100 AIR miles from your base, over statelines, or over 12 hours a day, you must maintain a log.
If you operate a comm. vehicle in excess of 10,000# Gross weight you must run declared gross weight reg, (the little white square stickers on the doors with 25, 35, 75, 80, etc. ) But if you own an F-450 ford for example that requires CA#, MCP, and or DOT etc. and you never exceed 10,000# operating weight with it, you don't need declared gross weight registration.
Examples: 1= A 3500 DRW ram with a factory p/u bed hauling any trailer less than 10,000 GVWR or a 5th wheel RV under 15,000GVWR needs no special permits or numbers. Technically you must stop at the open inspection area unless it says "no pick-ups"
2=The same truck with a Knapp utility box mounted to the back requires CA#, (MCP), and or DOT, and is a motortruck NOT a pick-up and must stop at all open inspections.
3=If either of the above is towing a 12,500GVWR flatbed with their Uncles Bobcat on it for example, they need a Class A commercial D. L. and all the appropriate CA, DOT #'s etc.
Clear as freaking mud. And this just scratches the surface. Please don't shoot the messenger.