Views: 0 Author: LUEN Groups Publish Time: 2025-05-07 Origin: Site
When it comes to trailer maintenance or upgrades, knowing how to measure an axle for a trailer, including torsion axles that utilize rubber cords and wheel bearings, is essential. Accurate trailer axle measurements help you find the right replacements. They also prevent tire wear and keep your trailer safe on the road. To replace a worn axle, upgrade for more capacity, or repair damage, start by understanding trailer axle sizes and how to identify them.
When your trailer is pulling to one side or showing uneven tire wear
After an accident or impact
When upgrading to handle more weight
Before ordering replacement parts or a new axle
Understanding how to measure trailer axles also helps when buying used trailers or verifying the specs of your current setup.
Getting the right trailer axle dimensions is not complicated, but it does require attention to detail. Here are the core measurements you'll need:
Definition: The hub face is the distance from the outside face of one hub (where the wheel rim sits) to the outside face of the opposite hub. This is sometimes called the track length.
How to measure trailer axle length:
Remove the wheels for clear access.
Hook your tape measure on the outside of the hub, where the rim contacts it.
Measure straight across to the exact same spot on the other side of the type of axle.
Do not measure to the back side of the hub.
Purpose: This measurement checks the axle’s width. It makes sure your wheels are properly placed under your trailer. It’s the most critical measurement for wheel alignment.
Definition: The spring center is the distance between the centers of the spring seats or pads on the axle. This is where the axle connects to the trailer’s leaf springs.
How to measure:
Measure from the center of one spring pad across to the center of the opposite pad.
Alternatively, measure from the outside of one leaf spring to the inside of the other (this gives the same result).
Why it matters: The spring center measurement ensures the axle will mount correctly to your trailer's suspension. If this is off, your axle won’t fit the frame.
Definition: The brake flange width is the distance between the outer faces of the brake flanges welded to the axle.
How to measure:
Hook your tape measure to the outside of one brake flange.
Measure across to the same spot on the opposite flange.
Purpose: This ensures your brakes will mount properly and align with the wheels.
How to measure an axle length:
Measure from one end of the axle (including the spindle) to the other.
This is especially useful if hubs or brakes are missing.
Definition: The bolt pattern is the number of lug studs and the diameter of the circle they form.
How to measure:
Count the number of lugs.
Measure the diameter of the circle that passes through the center of each lug.
Common bolt patterns:
3,500 lb axles: 5 lugs on a 4.5-inch circle
5,200 lb axles: 6 lugs on a 5.5-inch circle
7,000 lb axles: 8 lugs on a 6.5-inch circle
Why it matters: The correct bolt pattern ensures your wheels fit securely.
Sometimes, you need to measure a trailer axle when parts are missing or the axle is bent. Here are reliable methods:
Measure the distance between the spring centers.
Measure from the spring center to the end of the axle (overhang) on one side.
Formula: Hub Face = Spring Center + (Overhang × 2)
This method is helpful for estimating the hub face when you can't measure directly.
Measure between the outer faces of the brake flanges.
Add a standard adjustment (varies by axle size) to estimate the hub face.
Measure the full length of the axle.
Subtract a set amount (depending on axle capacity) to estimate the hub face.
These methods are especially useful for older or damaged trailers.
How to measure trailer axle diameter:
Use a tape measure or calipers to measure the axle tube from top to bottom.
Typical sizes and capacities:
Axle DiameterCapacityCommon Use1.75"2,000 lbsSmall utility2.375" (2 3/8")3,500 lbsSingle-axle trailers3"5,200-7,000 lbsTandem/Heavy duty, including spring axles where applicable.
Reference: Use a trailer axle diameter chart to confirm your axle's rating.
Why it matters: The diameter directly relates to how much weight your axle can safely carry.
Trailer axle sizes are standardized for safety and compatibility, and they are typically specified on the axle beam. Larger diameters mean higher weight ratings. Always check your trailer's VIN plate or the label on your axle for the official rating.
2,000 lb axles: light-duty, 1.75" diameter
3,500 lb axles: most common, 2 3/8" diameter
5,200-7,000 lb axles: heavy-duty, 3" diameter
Trailer axle size charts and trailer axle width charts can help you match your measurements to industry standards.
Axle drop: Measure the vertical distance between the axle tube and the spindle center. This affects ride height.
Mounting types: Know whether your axle is underslung (below the springs), overslung (above), or cambered (arched for load).
Use diagrams: A trailer axle measurement diagram or trailer axle diagram can clarify where to measure.
Double-check: Always verify your measurements before ordering parts.
Remove wheels and tires for clear access.
Measure hub face, spring center, brake flange, overall length, and bolt pattern.
Use alternative methods if components are missing.
Measure axle diameter to confirm weight capacity.
Reference trailer axle size charts and diagrams for accuracy.
When in doubt, consult a professional or the manufacturer.
Final Word: Knowing how to measure a trailer axle is a skill every trailer owner should have. If you're replacing, upgrading, or checking your setup, follow these steps. They help you find the right parts and keep your trailer safe on the road. Use this guide, along with diagrams and charts, for every trailer axle measurement. If you’re ever unsure, reach out to a reputable trailer parts supplier for help.
