Where To Measure the Axle To Determine the Weight Capacity

Question:

when determining trailer axle capacity ive seen the breakdown of axle weight ratings based on axle diameter, but what I need clarification on is which part of the axle should be measured. is it the tubular axle connecting both the hubs together or is it the spindles that the tires mount on? thank you

asked by: Justin K

Expert Reply:

In regards to determining axle capacity, the portion of the axle that will be measured is the cross beam, or rather the tube that connects the two sides together. If you were to measure where each bearings ride on the spindle that would then give you a much more exact weight capacity but for a general capacity, the diameter of the axle tube is sufficient. If you did however want to measure the spindle you would need to do so to the thousandth of an inch with a digital caliper.

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

expert reply by: Conner L