How to Determine Trailer Capacity using a VIN, Bearing Numbers, or Axle Diameter

Published 04/21/2014

Question:

I only have a VIN number from the title of a trailer someone is selling. Can I look up the weight rating using only that?

asked by: Wm. B

Expert Reply:

It is possible that the local DMV or license bureau has the information on the trailer so you will need to call them and see if they do have that information. If they do not there are other ways to determine axle capacity.

You can ask the seller for the inner and outer bearing numbers stamped into the metal of the bearings. With those numbers I can determine the likely capacity. Another method is to measure the axle diameter if it is a round axle (if its a square axle I would have to have the bearing numbers).

Typical Axle Diameters Based on Axle Capacity

1,000-lb - 2,000-lb Axles: 1-1/2" - 1-3/4" diameter
3,500-lb Axles: 2-3/8" diameter (Can have a 3-1/2" diameter, but rarely)
6,000-lb - 7,200-lb Axles: 3" diameter
8,000-lb Axles: 3-1/2" diameter
9,000-lb Axles: 4" diameter
10,000-lb Or more axles: 5" diameter

expert reply by: Michael H