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Truck lettering fonts: what reads from 50 feet and what doesn't

Short answerUse a bold block or sans-serif font with thick, even strokes and normal letter spacing, in a color that contrasts sharply with the paint. 49 CFR 390.21 doesn't name a font, but it requires the marking to contrast sharply with the background and be readily legible from 50 feet in daylight while the truck is parked. Script, thin and decorative fonts are the ones that fail that test.

What the rule says about fonts

Nothing by name. 49 CFR 390.21 requires the marking to appear on both sides of the self-propelled CMV, to be in letters that contrast sharply in color with the background, to be readily legible during daylight hours from 50 feet while the vehicle is stationary, and to be kept so it stays legible. Washington State Patrol's marking guide says the same and notes the rules give no minimum letter height. The font is up to you, as long as an officer can read it from 50 feet.

What makes letters readable at 50 feet

Heavy strokes. Thick, even lines keep their shape at a distance. Hairline strokes vanish.
Simple shapes. Block and sans-serif letters, where a 3 can't be mistaken for an 8 and a 1 doesn't look like a 7.
Open spacing. Letters packed tight blur together from across a lot. Normal spacing beats squeezing more text in.
Contrast. Dark letters on light paint or light letters on dark paint. Two similar shades fail the contrast part of the rule no matter the font. See color and size rules.
Height. See USDOT number size requirements.

Why script and thin fonts fail

Script fonts connect letters and vary stroke width, so numbers in particular get hard to read at a distance. Thin and light fonts don't put enough color on the door to read from 50 feet. Outlined or shadowed letters can look busy and blur together. Your logo can be as fancy as you want. The legal name and USDOT number are the lines that have to pass.

Condensed fonts for long names

A condensed font is a narrower version of a block font. It lets a long company name fit a short door without dropping the letter height. Keep the strokes heavy: a font squeezed too far gets thin and the letters crowd each other.

What our designer offers

Our designer offers block and condensed styles, built for the 50 foot test, and shows a live preview on a photo of your truck type before you order. It all ships as cut vinyl, one pre-spaced sheet per door. Start with USDOT door lettering.