Vehicle Marking Requirements: Getting Your USDOT Lettering Right

This one's simple. But we still see violations for it at scale houses, so apparently it's not simple enough. Under §390.21, every CMV must display specific information on both sides of the vehicle.

What Must Be Displayed

• Legal name or single trade name of the carrier
• USDOT number, preceded by "USDOT"
• If you're operating for hire, your MC number (optional but recommended)

Size and Format Rules

• Letters and numbers must be at least 2 inches tall
• Must be in a color that contrasts with the background (i.e., readable)
• Must be readable from 50 feet during daylight
• On both sides of the power unit (not trailer — the tractor)
• Can be painted, decaled, or magnetic

Magnetic Signs

Magnetic signs are legal. They're popular with owner-operators who lease to different carriers. Just make sure they actually stay on — highway speeds, vibration, and weather can knock them off. Losing your USDOT sign mid-trip means you're operating without markings until you notice. And if an inspector notices first...

Common Mistakes

• Displaying a trade name that doesn't match your FMCSA registration
• Faded or peeling decals that are no longer readable
• Displaying an old USDOT number from a previous carrier
• Missing markings on one side of the vehicle

Get good vinyl decals from a local sign shop. $30-$50 per truck. Lasts years. Way cheaper than the violation.