How To Measure Trailer Wheel Size: All You Need To Know

Wondering how to measure trailer wheel size?

If you’re planning to change your trailer’s tires, then you’ll need to know a few key things, including the bolt and lug patterns.

Fret not because I’m here to answer.

  • To measure the trailer wheel size, you will need to understand how to read the markings on the tires’ sidewalls.
  • The most common tire sizes for trailers are 8, 9, 10, and 12 inches.
  • These sizes include all the details, such as the tire profile and diameter.
  • Another critical aspect of measuring trailer wheel size is linked with the lug patterns. Depending on this, your tire size will vary.

Why Does Wheel Size Matter?

Before I dive into the guide, it is essential to understand why the wheel size is even a subject of concern and why it is important to get the correct tires.

men with trailer wheel in hand but how to measure trailer wheel size

In simplest terms, the wheel size determines the vehicle’s grip on the road. The larger the wheel size, the better grip it will have, thus the better handling.

Similarly, it affects ground clearance and the total weight that can be managed. If you buy a set of large and durable tires, then they will relatively be able to hold more weight. All in all, however, the wheel size is extremely important.

What Is The Usual Size Of Trailer Wheels?

This is quite a common question that I get. The general rule of thumb is to get as large tires as possible that fit with your trailer.

In essence, the wheels should have enough ground clearance not to cause friction between the trailer’s base and the road. This is specifically true when driving through speed breakers.

The most common horse trailer tire sizes are 8”, 10”, 12”, 13”, and 14”.

How To Read Your Wheel Size?

If you own a vehicle, then knowing what those numbers on the sidewall of the wheel represent is crucial. It can save you time and effort if you ever need to replace a wheel.

In essence, the wheel will have 7 different things represented as a code.

  • The first letter will represent the tire type.
  • The next three numbers represent tire width in millimeters
  • The next two numbers represent the aspect ratio
  • The next letter, which will be an alphabet, represents the construction type.
  • The next two numbers represent wheel diameter in inches
  • The next two numbers represent the load index
  • The last letter represents the speed rating

Therefore, if you want to measure the trailer wheel size, simply note the above details for your tire.

Learn more about how to measure trailer wheel size from the expert in this video.

READ MORE: How Often Should Trailer Tires Be Replaced?

What Lug Pattern Or Bolt Pattern Does My Trailer Have?

A bolt pattern or lug pattern represents the measurement of a circle that would be formed if all the lug holes lay on a circle. (1)

It is represented by two numbers where the first number represents the number of lug or bolt holes while the second number represents the circle’s diameter.

How Many Kinds Of Bolt Patterns Are There?

In essence, there are various kinds of lug patterns based on the number of lug holes. The most common ones are 4-lug, 5-lug, and 6-lug patterns.

To measure, check how many bolts the wheel has.

In case the wheel has an even number of bolts, measure the distance from one bolt to another. (2)

In case the wheel has an odd number of bolts, then you will measure the distance between two bolts directly across each other.

The result will give you the diameter. In essence, however, the bolt pattern will depend on the number of holes.

Is It Possible To Change Rims, and How?

Yes, you can. It helps to remember that vehicles with bigger rims can also be used with larger tires.

For this very reason, if you are planning to change your rim size, it is easily possible to do so with a few tools. Simply follow the steps below:

  • Using the flat side of the tire iron, pry off the rubber tread and use a screwdriver to loosen the lug nuts. Be careful not to damage the threads or the nut.
  • Once the lug nuts are loosened, remove them by turning counterclockwise. If they were seized at the factory, these lugs might need to be removed using a wrench.
  • Now turn the wheel over and remove the lock ring. You should now have access to the hub and axle.
  • Use a 1/4-inch drive socket to remove the bolt holding the bearing cup inside the hub.
  • Loosen the retaining nut and pull out the bearing cup.
  • Replace the bearing cup with a new one
  • Reinstall the lockring and tighten the retaining nut.
  • Tighten the lug nuts back down. Done!


What does the D stand for on a trailer tire?

In essence, the D stands for diagonal bias construction. If the tire has biased construction, then that means that the plies which were used for the tire are crisscrossed.
However, this is a traditional system because modern tires incorporate radial structure.

What Is The Difference Between Radial Construction and Bias Ply Construction?

Radial tires and bias are essentially two options, with bias tires made using cords of polyester and nylon belts that are crisscrossed.
On the other hand, radials are made by crisscrossing steel belts. The latter option is much better due to the structural integrity that it provides.

Should I Go For Larger or Smaller Wheels?

larger wheel for trailer but how to measure trailer wheel size

As we mentioned earlier, the larger the wheel size, the better. It will be slightly expensive; however, having a larger wheel will ensure better ground clearance and better handling on the road.


Whether you’re thinking of getting larger tires or replacing the old worn-out ones, knowing how to measure trailer wheel sizes can help a great deal.

In this guide, I went over the procedure to measure and read the tires, along with deciphering the codes on the sidewalls. That brings us to the end of this guide.

men checking how to measure trailer wheel size

Did you find the guide helpful? Let us know in the comments section!


  • 1. How to Measure your Trailer Wheels Bolt Pattern [Internet]. [cited 2022 Nov 10]. Available from:
  • 2. How to Measure Width and Bolt Pattern on a Trailer Wheel [Internet]. E Trailer. [cited 2022 Nov 10]. Available from:,to%20edge%20of%20the%20wheel.
Emily Donoho
Emily Donoho

Emily is a native of Colorado, currently living in Glasgow, Scotland, working as a freelance writer. She is a long-time horsewoman, having started riding at the age of 6, then competing in dressage around Colorado and Massachusetts, where she finished her undergraduate degree in psychology.

Following a move to the UK and a PhD, she worked for a few years as a freelance horse trainer in Central Scotland. She’s interested in holistic horsemanship, fostering better communication and understanding between horses and humans, riding with lightness and softness, and she’s forever seeking out the newest research into equine behavior and psychology. When not writing, she can be found at the barn with her two equine partners, Foinavon, an ex-feral Highland pony, and Hermosa, a young Andalusian.
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