What are the rules exactly? Let’s say you are leasing a semi, delivery van or courier vehicle for your logistics business. Since the truck is not something you personally own (or will ever own for that matter), you would like to limit the amount of alterations you make to the vehicle to insure a smooth transition when the terms of the lease expire. You also have to identify your vehicle with the proper GVW, MC, ICC or US DOT Numbers in order to be compliant with the DOT. According to the US DOT publication ETA 501c section 390.21 referencing vehicle identification the rule is this:

"Every commercial motor vehicle operated by a motor carrier in interstate commerce must be marked,

on BOTH sides of vehicle, with the following: 
вћ¤ The motor carrier’s name or trade name вћ¤ The motor carrier’s identification 
number, preceded by “US DOT” 
вћ¤ The size, shape and color markings must be in letters that contrast sharply in color with the background on which the letters are placed 
вћ¤ The lettering must be readily legible during daylight hours, from a distance of 50 feet."

 

* While it is true that the law does not specifically state a size or color requirement, it does say that it needs to be "legible" from 50 feet. The sign industry standard for block lettering to be read at 50 feet is 2" high. Other fonts and colors are perfectly legal, they just need to be sized a little larger to be read from a 50 foot distance.

Standard Ink Colors

Color Pallete


Transparent
Gloss White
Gloss Black
Golden Yellow
Sun Yellow
Signal Yellow
Maize Yellow
Yellow
Light Yellow
Brimstone Yellow
Cream
Light Ivory
Purple Red
Dark Red
Red
Tomato Red
Cardinal Red
Light Red
Blood Red
Middle Red
Signal Red
Orange Red
Red Orange
Orange
Pastel Orange
Bordeaux
Violet
Lilac
Pink
Telemagenta
Magenta
Soft Pink
Black Blue
Steel Blue
Dark Blue
Ultramarine Blue
Deep Blue
Cobalt Blue
King Blue
Brilliant Blue
Middle Blue
Blue
Traffic Blue
Gentian Blue
Azure Blue
Euro Blue
Light Blue
Ice Blue
Petrol
Turquoise Blue
Turquoise
Mint
Dark Green
Folliage Green
Emerald
Turquiose Green
Green
Grass Green
Light Green
Traffic Green
Mint Green
Yellow Green
Lime-Tree Green
Brown
Red Brown
Nut Brown
Light Brown
Komatsu Grey
Anthracite
Dark Grey
Iron Grey
Grey
Slate Grey
Telegrey
Middle Grey
Light Grey
Silver Grey