Your truck sits in a driveway for three hours while you swap a water heater. It sits at a red light on Manchester Road behind six cars. It sits in the Home Depot lot next to a contractor who is about to need a sub. That is a lot of eyeballs for a one-time cost, and most trucks waste it.
The mistake is almost always the same. Too much information, too small, all in one block on the door. Somebody reads two words of it at 40 miles an hour and then you are behind them and gone.
Here is how to think about it instead.
Three things, in this order
What you do. Where you do it. How to reach you.
That is the whole list. Everything else is decoration, and decoration is what pushes the important part down to a size nobody can read from another lane.
What you do goes first and biggest. Not your business name. If you are Kowalski and Sons, the word that makes somebody's head turn is PLUMBING, not KOWALSKI. Your name can ride above it in a smaller weight. The trade is the headline.
Use the word a customer would use, not the word on your license. Homeowners search for a garage door guy, not an overhead door systems specialist. They say drain cleaning, not hydro jetting, until somebody teaches them the second one. A painter who puts CABINET REFINISHING on the tailgate will get calls from people who did not know that was a thing you could pay for.
Where you do it matters more than people think out here. A pool service truck that says SERVING ST. LOUIS COUNTY tells a homeowner in Ballwin that you are not going to charge a trip fee to come out from across the river. If you cover a tight radius, say the towns. Eureka, Pacific, Wildwood on a door panel reads as neighbor, not as vendor.
How to reach you is the part worth arguing about, so it gets its own section below.
Test it from across the parking lot
Forget rules about letter height. Do this instead.
Park the truck. Walk backwards until you are about as far away as one lane of traffic plus a car length, then keep going another twenty paces. Turn around. Can you read the trade and the number in about two seconds, without squinting?
If not, something on that panel is too small, and the thing making it too small is usually a list of services in six-point type. Cut the list. Somebody who can read what you do and how to call you will ask about the rest.
Second test: have your spouse or your helper drive past it while you stand on the curb. Reading a stationary truck while you stand still is not the real condition.
The back door is different from the side
The side of the truck gets seen from a distance, at an angle, usually moving. Big and simple wins.
The back door gets seen by one person, stopped, at a light, for thirty to ninety seconds. That is the only surface where a second line of copy earns its keep. Auto repair shops use the tailgate for the thing that makes somebody pull out a phone: SAME DAY BRAKES. Cleaning companies use it for MOVE-OUT CLEANS. A barber with a mobile chair can put WE COME TO YOU back there.
Dark letters on a white truck read cleanest. If your truck is a dark color, a light-colored panel behind your lettering will do more for legibility than a fancier font ever will.
Number, website, or both
Nobody memorizes a phone number off a moving vehicle anymore. They take a picture of the tailgate at the light, or they remember one short thing and search it later.
So the number should be there, big, on the back. And the short thing should be a domain that survives being half remembered. If your business name is long, buy a short domain and forward it.
What to skip: a QR code on the side of a moving truck. It works parked at a job site where a neighbor walks over. It does nothing at 45 miles an hour. If you want one, put it on the yard sign, not the door.
Also skip the Facebook logo, the tiny license number crammed into a corner, and a list of every brand you carry. Check whatever rules apply to your trade and your area with your own advisor, but decorative clutter is a choice, and it is costing you letter height.
The lettering only works if somebody picks up
This is the part that makes truck wraps feel like a waste of money. The call comes in at 2:40 in the afternoon while you are on your back under a sink. It goes to voicemail. They saw four other trucks that week.
Work out what a missed call is worth to you from your own books. Take your last twenty completed jobs, add the invoices, divide by twenty. That is roughly your average ticket. Then guess honestly how many calls a week you let ring out. Multiply. Compare that to what your wrap cost. Most shops find the wrap was never the expensive part.
Before the wrap goes to the printer, write down what callers in your trade actually say. Garage door people hear "it goes up about a foot and stops." Pool guys hear "it's green." Electricians hear "half the kitchen is out." The words on your truck should sound like the problem the caller has, because a caller who recognizes their problem is a caller who dials.