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California truck lettering requirements
Short answer13 CCR 1256 requires the carrier name and the CA number preceded by 'CA' on both sides. The regulation exempts vehicles displaying a valid USDOT number from the CA-number line, but CHP inspectors expect both and every California carrier we know shows both.
What California requires
| USDOT for intrastate carriers | Yes, since September 2016, for vehicles 10,001 lbs and up used in commerce. |
|---|---|
| State number | CA number, from the DMV Motor Carrier Permit |
| Printed format | CA 123456 |
| Size | No inch minimum; legible from 50 feet in daylight with sharp contrast (49 CFR 390.21). Two inch numbers is the standard. |
| Enforced by | CHP (markings), California DMV (MCP) |
| Sources | 13 CCR 1256; CVC 34507.5; B&P 7029.6 |
What the door looks like
Your Company LLC
USDOT 1234567
CA 123456
Also worth knowing
- No inch height in the general rule; legible at 50 feet with sharp contrast. School buses: 2 inch.
- Contractors: CSLB name and license, 3/4 inch minimum (B&P 7029.6).
- Tow trucks: company name, city and phone as well.
The federal rule underneath
49 CFR 390.21 applies to every commercial motor vehicle in interstate commerce: legal or single trade name, the letters USDOT and the number, both sides of the power unit, contrasting color, legible from 50 feet in daylight while parked. No federal inch minimum. The MC number is not a federal marking requirement, and trailers don't need markings. States add to this; they don't replace it.
Checked September 2026. Plain-English summary of the regulations, not legal advice. Rules change; the citations above are where to confirm.