How to Determine GAWR of 2-1/2-Inch Square Axle By Using Bearing Numbers

Updated 09/11/2017 | Published 09/08/2017

Question:

I looked at your advice on estimating the GAWR i.e. Typical Axle Diameters Based on Axle Capacity - 1,000-lb - 2,000-lb Axles: 1-1/2 inch - 1-3/4 inch diameter - 3,500-lb Axles: 2-3/8 inch diameter - 6,000-lb - 7,200-lb Axles: 3 inch diameter - 8,000-lb Axles: 3-1/2 inch diameter - 9,000-lb Axles: 4 inch diameter - 10,000-lb Or more axles: 5 inch diameter Is there a table that relates to square tubing that is used for the axles? Thanks

asked by: Gerard N

Helpful Expert Reply:

Trailer axles made from square tubing tend not to be weight-rated as consistently as round axles. In other words there is more potential variance in the weight rating of a square axle; two axles of the same dimensions could easily be rated differently. A 1-1/2-inch square axle could be rated for 1800-lbs, 2000-lbs or 2200-lbs. A 2-1/2-inch square axle could be rated for 3500-lbs or possibly more.

You can get close to the axle rating if you know the bearings used in the hubs and/or the size of the drum brakes used on the axle. Either of these will get you in the ballpark. If you find the inner and outer bearing numbers you can refer to the linked page for hubs; if you can find a hub that uses the same bearings then that hub's rating will typically be half of the axle rating (since the axle uses two hubs that have a combined weight rating that matches the axle's).

Usually an axle has a sticker or plate that lists its rated capacity.

expert reply by: Adam R