How to Tell the Weight Rating of a Trailer Axle

Life's full of mysteries, but your trailer axle's weight rating shouldn't be one of them. Usually the question of weight capacity comes up when you need to replace your axle, but you may also just want to know what's on your trailer for your own peace of mind. Below, we'll show you some simple ways to identify your axle's weight capacity. Let's get started!

We'll show you how to:

Check the Sticker, Stamp, or Plate
Measure the Axle Tube Diameter
Check the Bolt Pattern
Check Your Wheel Bearings
Take Other Identifying Axle Measurements

1. Check the Sticker, Stamp, or Plate

If you're lucky, your axle will still have its sticker with the weight rating included. (It might clearly say "capacity," but if not, the term to look for is "GAWR" (Gross Axle Weight Rating). If you know your trailer's axles came stock from the manufacturer, you may also be able to check the sticker or plate on your trailer for this information.

If you don't have a weight rating sticker but you see a serial number stamped onto your axle, you can call the manufacturer and have them verify the capacity for you.

These are the most reliable (and easiest) ways to determine your axle's weight rating, so we always recommend them above other methods. However, if for some reason you absolutely can't use your sticker or serial number stamp, there are other identifying features that provide an idea of the axle's weight capacity. Let's look at how to obtain these "clues" below.

Stickers on a 3,500-lb axle (top) and 5,200-lb axle (bottom)

2. Measure the Axle Tube Diameter

For round axles, the tube diameter is a good indicator of the axle's capacity. For instance, an axle with a 2-3/8" diameter will have a 3,500-lb capacity.

(Note that this only works for round axles. If you have a square axle, the axle tube won't tell you much. In that case, you'll need to look at #3 and #4 below.)

The challenge here is that sometimes round axle dimensions do overlap. For instance, a 3" tube might belong to a 5,200-lb, 6,000-lb, or 7,000-lb axle (or in certain cases of 'upgraded tubes' by Grand Design, 3,500-lb). If the tube diameter points to different axle capacities, you've narrowed it down, but you can still gather more information to try and get closer.

Measuring axle tube diameter

3. Check the Bolt Pattern / Number of Lugs

Your wheel bolt pattern (or lug pattern) won't be the defining feature that will reveal your axle's weight capacity, but it can help narrow it down, especially in conjunction with the tube diameter.

For instance, if you have a 3" tube, you know your axle capacity falls somewhere in the 3,500-7,000-lb range. If you've also got 6 lugs, you know it's probably not a 7,000-lb axle, since most axles of that capacity have 8 lugs. So you're likely looking at either a 5,200 or 6,000-lb axle (or in the case of Grand Design's 'upgraded tubes' 3,500-lbs).

Not sure how to find your bolt hole pattern? Check out our guide here.

What Does Your Bolt Pattern Say About Your Trailer Axle?

4. Check Your Wheel Bearings

If your axle clues are still pointing in different directions, you can use your wheel bearings to make your selection in many cases, since certain bearings are very common to specific axle sizes. For instance, if your 3"-diameter axle has inner bearing 25580 and outer bearing 02475, you can deduce that you have a 7,000-lb axle.

Your bearing identification numbers should be stamped onto the bearings themselves, but if the numbers aren't legible, you'll need a digital caliper to take a precise measurement. (Learn more about identifying your bearings here.)

Inner and Outer Bearings on Trailer Axle

Bearing Numbers on Inner and Outer Axle Bearing

Bearing identification numbers on bearings

5. Take Other Identifying Axle Measurements

The above steps will help you narrow down your axle weight rating. However, if you're replacing an axle, weight capacity is only one part of choosing the correct replacement.

It's important that your new axle's dimensions are the same as your current axle's so that it fits properly under your trailer. Two crucial measurements are the hub face and spring center. If you're caught between two axle capacities (for instance, a 5,200 and 6,000-lb axle), these dimensions will also help you choose the correct replacement axle.

Learn how to properly measure your axle here.

Examples: Determining the Weight Rating of an Axle

Example Axle #1:

3" tube diameter = 5,200-7,000-lb axle
6 lugs = 3,500-6,000-lb axle
Inner bearing 25580 = multiple options
Outer bearing 14125A = 5,200-7,000-lb axle

The only axle capacities that fall within each of these ranges are 5,200-lb and 6,000-lb axles. So now, we'd need to measure our hub face and spring centers to choose the correct replacement between these two capacities.

Example Axle #2:

2-3/8" tube diameter = 3,500-lb axle

This one is straightforward—axles with 2-3/8" diameters are most often 3,500-lb axles.

About Amber S

As a content writer for etrailer, I might spend my morning loading and unloading a bike on five different bike racks to figure out which is easiest to use. I might be in the parking lot, taking pictures of an impressive RV battery setup our techs came across in the shop and discussing the benefits of the setup with the owner. I might spend an afternoon in a manufacturer training classes for some hands-on experience with new products, and then sit down to assemble all this information into a coherent article.

At etrailer, one of our core values is that we are always learning, and I learn something new every day. I start each morning with the goal in mind of taking all of this information and figuring out the best way to answer the questions people ask us (and the ones they don’t know to ask yet), and helping people get the solutions they need to make their lives easier, safer, and more fun. I’m a DIYer at heart, so it brings me great joy to help a fellow DIYer find what they’re looking for, whether that’s a product, an answer, or a community.

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Written by: Amber S

/Updated on: 5/18/22

Tirod3

8/6/2024

This is a great lookup to determine what we really have in the way of load capacity. I've been under the assumption my 5x8 tilt was a half ton yet by axle, lug, and what little of the paper tag on the tongue I could read it's actually a 3,500# trailer. This opens up a lot more potential for what I could use it for.The title etc has no definitive rating on it so using the features to determine capacity is a great method.

Jameson C.

8/6/2024

@Tirod3 That's a lot of weight for that small of a trailer!

Tirod3

8/7/2024

@JamesonC I was hauling half pallets of rock on it as the seller stated they were 2,000 pounds. Didn't even approach hitting the axle while hauling it. Came with a 2" coupler, 2 3/8" axle, five lug hubs. The paper tag on the tongue read X,500 pounds, the x being severely sun faded. Working auto parts I know not to rub labels too much - numbers disappear with just a few swipes. It sure looked like a 3. Bought it 2005 (who knew I would get an F150 from that year later?) from a local vendor who practically had to have their arm twisted to sell them. If they skimped, it was the salvage yard 15" takeoff rims with nearly bald tires. I've moved to white spokes with new trailer tires and they meet the load rating - apparently the standard to match the bolt pattern. Passenger tires haven't done well on this trailer, I've lost two (quite bald ones) due to tread separation. A bit more reassuring knowing they are now rated to match. Having repacked the bearings 18 mo ago I'm not quite ready to pull one off to verify numbers but I did note a bit of grease slung on the inside - 20 years worth. Still, tempted to do it and replace seals. In the day I had access to scales in a variety of places, now they are out of the way. Would like to get a tare weight to see what it is.

Tirod3

8/8/2024

I realized later that there could be another indicator of trailer weight capacity - springs. In general, with plenty of exceptions, the number of leaves in the spring pack indicates a range of capacity. More leaves, more capacity. I note the light springs have 1 or 2, 3,500 merit 3 to 4 leaves, and on up to 8 or more for really heavy trailers. In my case, I have 4 leaves on each pack. If memory serves, a small utility I used to own, only big enough to carry a car topper, had just one leaf each side. I also remember it was impossible to back it up. That was a Montgomery Wards about 1983, came with 8" tires. Throwing that out there for those to consider when determining capacity.

Lawrence T.

3/3/2024

I inherited a boat trailer dual axel. I'm converting it to be a small car hauler. The axels are square, five lug and neither axel has brakes. I'm trying to determine the weight capacity. Also being neither axle has brakes. Can brakes be added ?

Mike L.

3/4/2024

@LawrenceT If you can get me the reference numbers off the inner and outer bearing, we can pretty easily determine the axle's capacity. Since you have 5-bolt hubs, it's probably a 2000 or a 3500 lb axle, but the bearing numbers would confirm it. If your hubs have brake mounting flanges (a square plate behind the spindle) then brakes can easily be added. If not, you'll be best off replacing the axle. I'll link to an article that explains what parts are needed to add trailer brakes. Let us know if you have any questions!

Helpful Links

faq-adding-electric-drum-brakes.aspx

Kelly D.

11/23/2022

I have a dual axle flat trailer that I'm trying to figure weight capacity. The axles are both 3" I beams. The hub are 5 lugs...and I replace one of the front axle bearing when I repacked them it is a LM 11949. Can somebody tell me the load capacity...even close?

David B.

11/23/2022

Honestly I really can't say a good number my friend. I would try to find any kind of label/sticker/engraving/etching in the axles or trailer somewhere. If you can find a VIN you could call the manufacturer and find out.

John 6.

8/27/2023

@KellyD

Mike L.

8/30/2023

@John6 Did you have a question or comment?

Robert S.

5/22/2022

I'm looking for replacementI'm looking for replacement for this axle. LCi35-SBSA-85.5-68.5-NOSP -S0-L-545-7242-30PT v000112690 Would appreciate any help you can give me.

David B.

5/23/2022

I don't have an axle with a spring center to match that....That is the one measurement we need to be 100% the same. Have you thought about going axle-less? Have a look at the provided links and let me know what you think.

Helpful Links

question-331719.html

trailer-axles/timbren/asr3500s05.html

trailer-axles/timbren/asr3500s06.html

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