How to Measure Trailer Wheel Bolt Pattern?

Travel trailers go through a lot of adventures with you, enduring through thick and thin. Most parts can only take so much until they succumb to wear and tear. And trailer wheels belong to that category.

The first thing you need to know about your wheels after you figure out the size is the bolt pattern specifications. You need to know where to find or how to measure the bolt pattern of a wheel to be able to find a fitting replacement for it.

But don’t get discouraged yet. Measuring your wheel’s bolt pattern is simple and only takes a moment of your time. You can obtain precise measurements using either a ruler or a specialized bolt pattern gauge. However, the technique may vary based on whether you have an odd or even number of bolts on your wheel. We'll provide guidelines for both scenarios.

Most Common Trailer Wheel Bolt Patterns

A 5-bolt pattern of 4.5" is considered something of an industry standard for trailers. This pattern is likely to provide the best balance between strength and weight distribution. And these are the most important qualities of good trailer wheels.

This also means that if you are a lucky owner of this bolt pattern, you will have a lot of accessories to choose from. The most popular or widespread options always sell better, and manufacturers try to make additional products that fit them well.

But you can also find a 5.5" bolt pattern on some vehicles. It balances the weight differently, but what’s important for you is fitment. If you assume that your wheels are a standard 4.5" size and buy a new set, it won’t fit your hubs at all.

What Is a Trailer Wheel Bolt Pattern?

You can define a bolt pattern as the spacing between the opposite holes designed for lug bolts or studs. Imagine drawing a circle through each of these holes to measure it. However, these patterns are not one-size-fits-all. They vary among different cars.

When selecting new wheels, you need to ensure the bolt pattern aligns perfectly with the existing hub hole pattern. Otherwise, the wheel won't fit safely and cause all sorts of trouble. Lug nuts or studs depending on the vehicle's design, secure the wheel in place. Whether the car is in motion or stationary, these bolts bear the vehicle's entire weight.

Trailer wheel bolt patterns can be even or odd-numbered. That likely depends on the number of lug bolts per wheel.

How Do I Know What Wheels Fit My Trailer?

It's super important to get matching wheels for your trailer, but how do you make sure the wheels are actually compatible? It's fairly easy and you have a few options to choose from. Some of them involve special tools some don't.

Check the Trailer's Manual

The most obvious way to find out your real bolt pattern size is to check the manual. The manufacturers always include crucial information and the manual. You can always find specifications inside. And that's how you can get a precise size of a bolt pattern to eventually choose a fitting set of wheels. But there is a catch. If your trailer has modified wheels, the manual might be a little last useful to you. And you should use a different approach.

Measure The Wheel’s Bolt Pattern

The wheel itself has all the information you need to know. Grab that bolt pattern gauge or a ruler and go measure. If you have an even-numbered pattern on your trailer's wheels, measure the distance between two opposite lug bolts. If you have odd-numbered wheels, the method is a little different. But don't worry, we have you covered a little later.

Browse Online

Not everybody has their owner's manual readily waiting inside the vehicle. But there is another place you can find the same information you have inside the manual and it’s online databases. There are numerous websites that provide the information. All you have to do is pick one and set the filters correctly.

But is trailer bolt pattern size the only thing you need to know about your wheels to replace them successfully? Of course not. To ensure good fitment, you need to know specifications like wheel offset, PCD, width and diameter load capacity and tire size.

Do All Trailers Have The Same Bolt Pattern?

Actually, no, not all trailers have the same bulk pattern. The most common bolt patterns you're going to see on the wheels of a trailer are 4, 5, 6 and sometimes 8-lug patterns. Of course, the 5-lug bolt pattern it's probably the most common of them. Most trailers use a 5.4" 5-lug bolt pattern.

The trailer wheel's bolt patterns very depending on the number of lug bolts and pitch circle diameter or PCD. 4, 6 and 8 are even-numbered patterns you can commonly see on the trailer. With the only exception of a 5-lug bolt pattern that's odd-numbered requires you to know a certain technique to measure it.

The single-digit number refers to the number of lug bolts on the wheel. While the PCD is an imaginary circle that passes through the center of each bolt hole inference a pitch circle diameter connecting all of them.

These numbers will vary from one trailer to another depending on its size, weight distribution, etc. Ideally, you need to know both of those numbers to find a fitting replacement. It's not that hard to measure or look up. For instance, a 5x4.5 bolt pattern means the wheel has five bolt holes, and they form a circle with a diameter of 4.5 inches.

Can You Change The Bolt Pattern On A Trailer?

Certainly, the bolt pattern on a trailer can be altered, but whether or not it's worth it, you need to decide for yourself. Because there are some things you need to be careful with. And safety just so happens to be one of them.

As you know, a mismatched bolt pattern can stand in the way of secure fitment. This can potentially lead to dangerous situations.

There are several ways you can change the bolt pattern of a trailer's wheel. Each has its own unique benefits and disadvantages.

Hub Swap

The main problem with mismatched wheels is that they don't exactly match the hub. So naturally, you could swap the hub to make them compatible.

It's not a cheap method neither is a simple. But it gives you results.

Wheel Adapters

We adapters are a much more popular option. It's cheaper and simpler. Wheel adapters can help you alter the bolt pattern the way you want it. But the safety concerns come with the package.

Some shops and respectable mechanics advised against using wheel adapters. The materials used to make wheel adapters are not quite suitable for high-stress situations like cornering or hauling heavy loads. They are prone to damage and deterioration. This becomes a major problem for larger trailers.

If the wheel adapters fail, you can expect anything, including wheel separation in the middle of the road. That sounds like a situation you would really want to avoid. Of course, not all wheel spacers are made out of junk, but personally, I would recommend staying away from such modifications.

How to Measure a 4-lug Trailer Wheel Pattern?

Measuring a 4-lug trailer wheel pattern is straightforward. Take a reliable bolt pattern gauge and measure the distance from the center of one lug to the center of the lug opposite it.

For even-numbered lug patterns, the lug holes are typically directly across from each other, simplifying the measurement process.

To determine your trailer wheel bolt pattern's PCD (pitch center diameter), note the distance between the centers of the two opposite lug holes and the total number of lugs. For instance, if you measure 100mm between the opposite lugs on a 4-lug pattern, the PCD is 4x100.

How to Measure a 5-lug Trailer Wheel Pattern?

Though measuring an odd-numbered lug pattern is slightly different, it isn't particularly challenging. Unlike even-numbered patterns, an odd-numbered one doesn't have lugs directly opposite each other.

To find the size of a 5-lug trailer wheel pattern, measure from the backside of one lug to the center of the third lug. Consider the star pattern you'd use when tightening lug nuts. This same method will guide you in selecting the correct lug pair for measurement.

How to Measure a 6-lug Trailer Wheel Pattern?

Given its even number, a 6-lug trailer wheel pattern is similar to the 4-lug pattern. Measure the distance between the centers of two opposite lug holes.

This pattern is prevalent, especially in some larger trailers or utility vehicles. The typical diameter of this circle is around 5.5 inches.

How to Measure an 8-lug Trailer Wheel Pattern?

As you may have anticipated, measuring an 8-lug trailer wheel pattern follows the same logic as other even-numbered patterns. Simply determine the distance between the centers of two opposing lug holes. Commonly, this pattern's bolt circle measures about 6.5 inches.

What Tools Are Used to Measure Traier Bolt Patterns?

Being able to measure your bold pattern size on the trailer wheels is an essential skill. Your RV needs a perfect match because otherwise, the wheels will not fit perfectly and cause all sorts of trouble. So we know how to measure the bolt pattern size, but what do you measure it with?

There are not that many tools you can use to complete the task. And all those two tools are pretty simple and affordable.

Bolt Pattern Gauge

A bolt pattern gauge is hands down the best tool designed specifically for measuring wheel bolt patterns. It usually comes with various pegs or holes corresponding to different bolt patterns, allowing you to find a match for the wheel.

They can be made of plastic, metal or aluminum. This is a cheap and useful tool you can add to the garage collection.

Caliper or Ruler

For the DIY enthusiast or if you don't have a bolt pattern gauge, a caliper can provide a precise measurement between bolt holes. Digital calipers are especially accurate and can give measurement readings in both inches and millimeters.

If you're in a pinch, a regular ruler or measuring tape can also be used, though it might not be as accurate as a caliper. Make a second or even third round of measurement to make sure you got it right.

Bolt Pattern Template

These are flat templates with pre-drilled holes meant for various bolt patterns. By fitting them onto the wheel's lugs, you can identify the bolt pattern. They can be particularly useful when dealing with a large number of wheel types.

You can find them online with no issue. They come in all material options and colors.

Bolt Pattern Pro

This is a more advanced and comprehensive version of the bolt pattern gauge. It can measure both the bolt pattern and the stud size, making it an excellent tool for professionals and enthusiasts alike.

Circle Tool or Compass

Especially for odd-numbered lug patterns, using a compass can be helpful. By drawing circles that intersect through lug centers, you can find the diameter more easily.

Paper and Pencil

In the absence of specialized tools, placing a piece of paper over the lugs and marking the center of each lug with a pencil can give a visual representation of the bolt pattern. Once marked, the paper can be removed, and the distances between the marks can be measured with a ruler.