How many characters is a trailer VIN?

Seventeen, the same as cars and trucks. Older trailers (before 1981) may have shorter serial numbers that aren’t VINs in today’s format.

Which letters can’t be in a VIN?

I, O and Q are never used, so they can’t be confused with 1 and 0. Position 10 also never uses U, Z or 0.

What do positions 4 to 8 mean on a trailer?

Whatever the manufacturer’s VIN chart says. For trailers they usually encode the type of trailer, body type, length and axles, but the codes differ from one builder to the next.

Trailer VIN format explained, position by position (CMVSS 115)

Updated 2026-10-05 · By the VINready team, built by a Canadian trailer manufacturer

Every trailer built for road use in Canada carries a 17-character VIN set out by CMVSS 115, which follows the same layout as the US rules (49 CFR Part 565). Here’s what each position means, using the sample VIN XX9ZAFCLXV1123001.

Positions	Part	What it means
1–3	World manufacturer identifier (WMI)	Identifies the manufacturer. The first character is the region: 1, 4 or 5 for the United States, 2 for Canada, 3 for Mexico.
4–8	Vehicle descriptor section	The manufacturer’s own codes describing the trailer: usually type, body, length and axle setup.
9	Check digit	0–9 or X, calculated from the other 16 characters so typing mistakes can be caught.
10	Model year	One character from a 30-year cycle, for example V for 2027.
11	Plant code	The manufacturer’s code for the plant that built the trailer.
12–17	Serial number	The production sequence number. For low-volume manufacturers, 12–14 is the manufacturer identifier and 15–17 the serial.

The sample VIN, piece by piece

XX9: world manufacturer identifier. Yours, from Transport Canada. Ending in 9 means low-volume.
ZAFCL: positions 4–8. Size, body, axles and the rest, from the options you pick.
X: check digit. Calculated from the other 16. An X here means 10.
V: model year. V is 2027. The letter changes with the year.
1: plant code. Where the trailer is built.
123: manufacturer id. Low-volume makers’ 3-digit ID.
001: serial. The next one in line, never doubled up, even if two people issue at once.

Low-volume layout (a 9 in position 3)

Most trailer builders make fewer than 1,000 vehicles a year, so they use the low-volume layout: the WMI’s third character is 9, positions 12–14 are the manufacturer identifier, and only 15–17 count up. That gives 999 serial numbers per model year. A larger manufacturer uses all six of positions 12–17 for the serial.

Rules every VIN follows

Exactly 17 characters, capital letters and digits only.
No I, O or Q anywhere; no U, Z or 0 in position 10.
Position 9 must match the check digit calculation.
A VIN is never reused: no two vehicles share one within 30 years.

Want to test one? Paste it into the trailer VIN checker.

Common questions

How many characters is a trailer VIN?: Seventeen, the same as cars and trucks. Older trailers (before 1981) may have shorter serial numbers that aren’t VINs in today’s format.
Which letters can’t be in a VIN?: I, O and Q are never used, so they can’t be confused with 1 and 0. Position 10 also never uses U, Z or 0.
What do positions 4 to 8 mean on a trailer?: Whatever the manufacturer’s VIN chart says. For trailers they usually encode the type of trailer, body type, length and axles, but the codes differ from one builder to the next.

This guide explains the rules in plain language and isn’t legal advice. The Motor Vehicle Safety Regulations and Transport Canada’s guidance are the final word; check them, or ask Transport Canada, before relying on a detail.