How to measure a truck door for lettering

What you're measuring

Not the whole door. You want the flat, smooth rectangle where the lettering can sit without crossing anything. Vinyl sticks best to smooth paint, and letters that run over a handle or a body line get cut, wrinkle or lift.

Things to measure around:

• Door handles and lock cylinders
• Body lines, creases and ridges stamped into the door
• Rivets and seams, common on box truck and older cab doors
• Mirror mounts, trim strips, step plates and the window frame

3M's application bulletin says not to let the edge of a graphic fall on a rivet, to have the film extend at least 1/2 inch past a rivet when you do cover one, and to slit film along every seam. Easier to plan around them from the start.

How to measure, step by step

1. Clean the door so you can see every line.
2. Find the biggest flat rectangle, usually the lower middle of the door, below the window and away from the handle.
3. Measure its width at the narrowest point, in inches.
4. Measure its height, in inches.
5. Check the passenger door too. Mirror and step placement can differ side to side.
6. Take a straight-on photo of each door with the tape measure in the shot.

Masking tape helps. Tape the corners of the space you plan to use and step back. If it looks cramped from 20 feet away, it'll look worse with letters in it.

Door styles

• Semi tractor. Usually a good flat panel below the window. Watch for the handle, the step and any chrome trim.
• Box truck. The cab door is often smaller than people expect. Some owners letter the box side instead, which can have rivets and seams. Measure between them. See box truck lettering.
• Pickup. Doors often have a strong body line through the middle. Measure the flat area above or below it, not across it.
• Cargo van. Front doors are short. The sliding door or side panel may give you more room, but the marking still goes on both sides.

We don't publish standard door dimensions because they vary by make, model, year and cab. Measure your own truck.

How size relates

The federal rule has no inch minimum. It requires sharp contrast and legibility from 50 feet in daylight while parked, on both sides of the power unit. Some states add their own number. Texas DPS, for example, cites a state statute requiring letters and numbers at least two inches high for vehicles it covers. For how to pick a height, see USDOT number size requirements.

Our sizes go by number height: Small (1.5 in), Medium (2 in) and Large (2.5 in). The name line and any extra lines add height and width, so more lines need a bigger flat area.

Check it before you order

Our designer shows a live preview on a photo of your truck type before you order, so you can see how the lines sit on the door. Each door ships as one pre-spaced sheet, so once you know where the flat area is, application is about 15 minutes a door. Start with USDOT door lettering.