How can I determine my boat trailer’s axle type and size?

There are a few ways to identify what axle is on your trailer.

Is it round tube or square tube?

One of the quickest ways to identify your axle is by looking at the shape of the tube.

Square Tube Axle: Stronger sidewall support, commonly used for torsion axles.
Round Tube Axle: More common in spring axles, designed for flexible suspension.

What size tubing is it?

Axle tubing comes in different sizes. Measuring the outside dimensions helps confirm which axle you have.

Common Sizes We Carry:

Square Tubing: 1.5″ x 1.5″, 2″ x 2″, 2″ x 3″
Round Tubing: 2″, 2.75″

How do I measure hub face, brake flange, and spring centers?

Hub Face (Track) Measurement:

Measure from the outside of one hub face (where the wheel rim rests) to the outside of the opposite hub face.

For accuracy, remove the tire assemblies before measuring.

⚠️ Do not measure to the back side of the hub.

Brake Flange Measurement:

Measure from the outside of one brake flange (welded to the axle) across to the outside of the opposite flange.
⚠️ Do not measure to the back side of the flanges.

Spring Center Measurement (spring axles only):

Measure from the center of one leaf spring pad to the center of the opposite pad across the axle.

Having a second person hold the tape measure can make this easier.
If working alone, measure from the outside of one pad to the inside of the opposite pad—this gives the same result as center-to-center.

Do I have a straight axle or a drop-center axle?

Trailer axles generally come in two styles: straight axles and drop-center (V-bend) axles.

Straight Axle: Runs in a straight line from hub to hub. Commonly used for lighter trailers or when maximum ground clearance is needed.
Drop-Center Axle (V-Bend): Has a bend in the center, lowering the trailer’s deck height. This improves stability and makes loading easier but reduces ground clearance.

Look at your axle from the side: if it’s perfectly straight across, it’s a straight axle. If it has a visible bend in the middle, it’s a drop-center axle (as shown in the diagram)