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Nov 13 2018

In comparison to passenger vehicles with currently 40 manufacturers, trailers are made by hundreds of manufacturers in North America and each has numerous configurations. Commercial VIN decoding solutions for trailers are rare because of the effort required to obtain this data as well as the differences in how the VIN is used. However, they do exist!

As you search for the best commercial trailer VIN decoding solution, it’s important that you understand what information can be obtained from the VIN. In this article, we will cover the key information you need to know about trailer VIN decoding, including where you can find the VIN, which details can and cannot be identified by VIN, and which details are sometimes, but not consistently, encoded.

What is a trailer VIN and what’s captured?

Just like a vehicle VIN number, a trailer VIN is a unique identifier of the trailer. The NHTSA requires all trailers destined for traveling on the road to be assigned a 17-digit VIN. Though both vehicles and trailers are required to have VINs, what’s encoded within those 17 characters varies quite a bit given their obvious differences. Below is the breakdown of a typical trailer VIN and you can view the breakdown of a vehicle VIN number here.


Please note that the letters I, O, and Q will never appear on a trailer (or vehicle) VIN because they can get mixed up with the numbers 0 and 1.

Here is a detailed breakdown of a trailer VIN:

World Manufacturer Identifier (1-3)

Positions 1-3 are the company identifier characters, also known as the World Manufacturer Identifier (WMI). These first three characters cover the make of the trailer and the country it was manufactured in.

Make / Country of Manufacture

Position 1 identifies the country in which the trailer was manufactured. Coupling position 1 with position 11 (Plant) allows for greater specificity of the actual location down to the city and state.

Positions 1-3 are all used to identify the manufacturer (also known as the make) of the trailer, unless the 3rd position is the character "9". Position 3 will always have the number 9 for smaller manufacturers who make less than 1000 trailers per year and share the WMI with other small manufacturers. Identifying these companies by VIN is still possible, however, it would require a change of VIN decoding structure.  Therefore, most trailer VIN decoding solutions don’t support coverage of these manufacturers.

Vehicle Descriptor Section (4-8)

Positions 4-8 make up the Vehicle Descriptor Section which is dedicated to providing certain key specifications on the trailer. This section is subject to vary across manufacturers and trailer types, however, there are certain fields such as trailer type, length, and number of axles that are required. Here’s what a typical vehicle descriptor section will look like:

Trailer Type / Attachment (Product Line)

Positions 4 and 5 are the trailer product line characters. The product line is made up of the trailer attachment type (ex. kingpin, ball, gooseneck, etc) and trailer type (ex. platform/flatbed, utility, dump, vehicle carrier, etc).

Trailer Length

Positions 6 and 7 encode the length of the trailer. Although these two characters are typically both numeric (such as the VIN sample above), they do not necessarily represent the length (45ft.). Instead, they are merely characters used to encode the length. In most cases, the trailer will have a single length, typically rounded to the nearest foot. However, there are some exceptions where the manufacturer will give a length range, for example, a 2009 Wells Cargo utility trailer with a length range of 16-19ft.

Number of Axles

Position 8 is where the number of axles is encoded. The axle count may be useful within tax/registration fee scenarios by state agencies or for insurance purposes.

Remaining Characters (9-17)

The remainder of the VIN is made up of the check digit, model year, plant, and serial number.

Check Digit (9)

Position 9 is the check digit. The check digit helps verify the validity of a given VIN number using a checksum algorithm put in place by the NHTSA in 1981. Some of the most common reasons for failing the checksum test are due to typos in the VIN, invalid characters, or missing characters.

Year of Manufacture (10)

Position 10 is where the year the trailer was manufactured is encoded.

Production Plant (11)

Position 11 indicates which plant the trailer was manufactured at.

Serial Number (12-17)

Just like any other 17-digit VIN number, the last 6 positions (12-17) are the trailer's serial number. The serial number is what makes each VIN unique, since the VIN pattern or squish (positions 1-8, 10, and 11) will be the same, for the most part, for multiple VINs representing the same trailer model in a given year.

Where is the VIN located?

A trailer’s VIN number is most commonly located near the attachment point of the vehicle and trailer. This could be on the frame rail or directly on the body of certain trailer types, and will likely be found in one of these three forms:

  • In the trailer identifier plate/plaque along with all the other trailer information, including the model number and certain specifications.
  • Printed on a VIN sticker. Some manufacturers do this, despite it being more susceptible to damage or loss.
  • Stamped directly into the metal of the trailer. This method is not the best since it can be hard to read as the trailer wears over time.

What other data can a trailer VIN decoding solution identify?

As shown in the trailer VIN breakdown above, year, make, trailer attachment, trailer type, length, axles, and production plant can all be identified from the trailer’s VIN alone. However, some trailer VIN decoding solutions, including DataOne’s, can identify some additional ancillary data that appears for certain trailers, such as trailer material (ex. aluminum, steel), liquid/dry volume (for tanker/dry bulk trailers), and DOT specification (for tanker/dry bulk trailers). The DOT specification will be particularly valuable for registration and insurance companies and can be identified almost 50% of the time for tanker/dry bulk trailers by VIN squish (also known as VIN pattern). 


In many cases, a trailer will be customized after manufacturing. For example, a trailer might be manufactured as a utility trailer and then later upfitted as a specialized woodchipper. Unfortunately, this information cannot be identified by VIN since the VIN is assigned at the time of manufacturing.

Where can I decode trailers?

As mentioned previously, there aren’t many options for trailer VIN decoding on the market today. For single trailer decodes, a free decoder on a website such as the NHTSA or DMV will be your best option. As for trailer VIN decoding solutions that can be licensed via a web service API or delivered database, those are even harder to come by from a reliable commercial source.

DataOne provides a trailer VIN decoding solution that covers over 1000 trailer manufacturers destined for use in the U.S. market back to the model year 1981 (when the NHTSA standardized the 17-digit VIN). This is the ideal business solution, giving the end-user flexibility to decode VINs in real-time or through batch processing.


It is important to understand what information is and isn't available from a trailer VIN to set correct expectations for your business case. While a great deal of information can be tied to some brands of trailers, it’s good to know that in your best-case scenario you'll likely be able to rely on just the following fields: year, make, type, subtype, trailer attachment type, length range, and axle count.

It is also important to understand what kind of coverage would be needed by a potential data source to be considered comprehensive enough for your requirements. A quick check of manufacturer coverage and types of trailers should yield numbers in the range of 800+ manufacturers and as many as 50 different trailer types/subtypes. Given the level of upfitting (post-factory), the VIN will not be able to identify every spec of the trailer as it has been upfitted but will be helpful for identifying some of the key information related to the specification as it left the factory.

If your business or agency is looking for a commercial VIN decoding solution, we hope this article is of use to you as you shop for a commercial source to meet your unique needs. Of course, we would be happy to help!


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