Operating a commercial vehicle out of Indiana? You’re subject to FMCSA federal door-marking rules plus a small set of Indiana-specific requirements for your USDOT decal. This page walks you through legal sizing, font, placement, and the most common reasons fleets get flagged at roadside inspections.
Federal FMCSA Rules (49 CFR 390.21)
Every commercial motor vehicle (CMV) operating in interstate commerce must display the USDOT number on both sides of the power unit. The minimum federal requirements:
- Letter height: at least 2 inches tall
- Contrast: letters must sharply contrast with the vehicle background color
- Visibility: readable from 50 feet during daylight while the vehicle is stationary
- Marking format:
USDOT 1234567with the carrier’s legal name above - Permanence: paint, vinyl decal, or magnetic sign, but the marking must stay legible
Indiana-Specific Add-Ons
Indiana follows the federal standard for interstate carriers but adds requirements for intrastate-only carriers. If you operate exclusively within Indiana state lines:
- Display
IN DOTfollowed by your assigned Indiana DOT number, in addition to (or in place of) USDOT marking - Letter height stays at 2 inches minimum
- Carriers transporting hazardous materials must register with the Indiana State Police’s Motor Carrier Services Division
Indiana also requires the name of the city, town, or county the carrier is operating from to appear with the USDOT number on certain motor carrier classes. Check your specific operating authority before applying decals.
Decal Size, Font, and Contrast
While 2 inches is the legal minimum, most Indiana fleets use 3-inch decals for cleaner visibility and better aging behavior, vinyl letters under 2 inches degrade visibility faster as edges fade.
| Vehicle type | Recommended height | Recommended font |
|---|---|---|
| Box truck / step van | 3″ | Helvetica Bold, Arial Black |
| Pickup with service body | 2″–3″ | Helvetica Bold, Impact |
| Heavy semi-tractor | 3″–4″ | Helvetica Bold |
| Trailer (mounted on door) | 2″ | Helvetica Bold |
Avoid script, condensed, or italic fonts on USDOT markings. DOT inspectors interpret these as non-compliant by default.
Where to Place the Decal
Place the decal on both sides of the power unit (driver door + passenger door is the standard location). Keep the letters within the door panel, placement on glass, fenders, or rear panels does not satisfy 390.21.
Spacing guidance:
- Carrier name on top line, USDOT number on the bottom line
- Equal margins (≥3 inches) from any door edge
- Avoid placing across handles, locks, or trim seams
Penalties for Non-Compliance
FMCSA can issue out-of-service orders and civil penalties up to $1,496 per violation per day (2026 rate). Indiana State Police Motor Carrier officers also conduct roadside inspections at weigh stations and can:
- Place the vehicle out-of-service until corrected
- Issue fix-it tickets requiring proof of correction within 30 days
- Trigger a CSA score increase that affects insurance rates
Frequently Asked Questions
Do I need a USDOT number for my pickup?
If the pickup is used in interstate commerce and meets the GVWR / hazmat / passenger thresholds in 49 CFR 390.5, yes. Indiana intrastate carriers may need only an Indiana DOT number.
Can I use magnetic USDOT signs instead of permanent vinyl?
Yes: magnetic markings are FMCSA-compliant as long as they remain legible from 50 feet. Many Indiana fleets prefer reusable magnets for vehicles that change branding.
What font is FMCSA-approved?
FMCSA does not specify a font. The rule is sharp contrast and 2-inch minimum height with letters that are clearly legible, stick with Helvetica Bold, Arial Black, or Impact in upper-case.
How long does USDOT vinyl last in Indiana weather?
Premium 6-mil cast vinyl rated for outdoor use lasts 6–7 years even with Indiana freeze-thaw cycles. Standard calendared vinyl gives 3–4 years.
Order Your Indiana USDOT Decals
Hoosier Decal designs and ships USDOT door decals from our Spencer, Indiana shop. Use our online designer to set your DOT number, choose a 6-year outdoor vinyl, and pick the color that contrasts your vehicle.
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