How to Measure a Trailer Axle

All trailer owners need to know how to measure their trailer axle, especially when it comes time to repair or replace this crucial part. Let’s learn the key dimensions to measure. 

Measure the Hub Faces

This is one of the most important measurements you’ll need to make on your axle. Measure from the outside edge of one hub to the outside edge of the opposite hub on the other end of the axle. 

How to Measure if You’re Missing Axle Hubs

Sometimes, you have to make a measurement but you don’t have hubs. Measure brake flange to brake flange when this happens. Flanges are at the end of each axle under where the hub typically sits. Measure outside face to outside face of each flange. 

Check this page if you have questions, too. 

Now Add Space for a Hub:

Inches to Add for Each Axle Capacity:

• 2,000 lb axles - 7 inches
• 3,500 lb axles - 6 inches
• 6,000 lb axles - 9 inches
• 7,000 lb axles - 9 inches
• 8,000 lb axles - 9 - 10 inches

Measure Spring Centers for Proper Placement

This is one of the most important measurements you will make in this project. The spring centers have to be in the exact same place as the old ones. If not, they might block wheels, tires, or other mechanical components. Measure from center to center of each axle spring. 

Measure Spindles End to End

With wheels removed, hook your tape measure on one spindle and measure outside to outside on the opposite spindle. 

Measure Tube Diameter

Trailer axle diameter corresponds to capacity. For 1k to 2k 1.5 to 1.75 inches is common. For 3.5k, 2-⅜ inches is common. Expect to see 3” diameter for 5.2 to 7k axles. For 8k, expect 3.5. For 9k, expect 4 inches, and for 10k axles, 5 inches. 

Tells The Trailer Parts Outlet What Information You’re Starting With

Figuring out which axle you need can be a little bit like an algebra problem. When you’re replacing a trailer, sometimes you have a different piece of the puzzle each time. Especially if your axle is damaged, or if you bought it used in a private sale. So call The Trailer Parts Outlet or write us and tell us what you’re starting with. We will help you replace your trailer axle!