Beyond the Size

Trailer Tire Sizes: How to Choose the Right One for Your Trailer

Trailer Tire Sizes: Everything You Need to Know

When it comes to towing a trailer, the tires are often overlooked. Choosing the right tire for your trailer is much more important than you may think.

A proper tire selection can make all the difference in improving trailer performance, reliability, safety, and fuel efficiency. This article will provide an overview of trailer tire sizes and why it is important to choose the correct trailer tires.

Trailer Tire Sizes

Rim Size Groups

Trailers with larger wheels may require different tires than those with smaller wheels. Before selecting a tire, you will need to know the rim size of your trailer.

Typically, trailer rims range from 12 inches and under to 13 inches and above. Knowing this information can help you select the appropriate tire for your trailer.

Standard Trailer Tire Size

When selecting a tire, it is important to consider several factors such as rim diameter, tire size, rim width, load capacity, and total diameter. The tire size should be the right fit for your trailer’s rim size, as well as being able to support the maximum load capacity of your trailer.

Tires with a larger diameter can provide better fuel efficiency and can help make the ride smoother.

Understanding Tire Codes

Tire codes can provide important information about a tire’s specifications. The codes include a service type, width, aspect ratio, construction, rim size, load index, speed rating, load range, and extras.

A service type refers to the intended use of the tire, such as whether it is meant for highway or off-road use. The width of the tire is measured in millimeters, and the aspect ratio refers to the tire’s height compared to its width.

The construction of the tire refers to the layers of materials used to make the tire, which can impact its performance and durability. The rim size is the diameter of the rim the tire fits onto.

The tire load index is the maximum weight each tire can carry, and it is important to ensure that the tire being selected has a load index rating that exceeds the total weight of your trailer. The speed rating is the maximum speed the tire can safely support.

The load range indicates the tire’s ability to withstand weight, and finally, extras such as ply ratings or steel belts can indicate the tire’s durability and performance capabilities.

Importance of Choosing Correct Trailer Tires

Risks of Choosing Incorrect Tires

Choosing the wrong tire for your trailer can be very risky and can result in drops in loading capacity, which can be dangerous. Unwarranted pressure on the tire can cause the rubber to explode, which can lead to serious harm and damage.

Consequences of Incorrect Tire Choice

When choosing the wrong tire, you are at risk of causing devastating results. If the tire fails, it can cause an accident, leading to injuries to you, your passengers, and other road users.

It can also lead to significant expenses such as repairs and medical bills.

Need for Exact Specification

To avoid these risks and consequences, it is important to choose the exact trailer tire specification that matches the rim size, tire size, load capacity, and overall trailer specifications. This is the best approach to ensure that your trailer runs efficiently, and there is less risk of compromising safety and overall performance.

Final Thoughts

Choosing the right trailer tire can make a significant difference in terms of safety and performance. It is important to consider the size, load capacity, speed rating, and any other factors that may be relevant to your specific trailer’s make and model.

Sticking to the exact tire specification recommended by the manufacturer is the best approach. This may seem like a minor detail, but it can have a significant impact on your trailer’s overall safety and performance.

When it comes to choosing trailer tires, safety should always be a top priority.

Trailer Tire Size Chart – Finding the Perfect Fit

Selecting the perfect trailer tire requires you to consider specific factors like the tire size, rim diameter, and load capacity. To ensure that you pick the right tire for your trailer, you must understand the differences between the available options.

In this article, well explore trailer tire size charts and decoding tire codes to help you make an informed decision.

12 Inches and Under

Trailers that require 12 inch and under rims are typically smaller trailers. The most common tire size for these trailers is 4.80-12 and is best suited for utility trailers, boat trailers, and double jet ski trailers.

The 4.80-12 tire size has a total diameter of 20.7 inches and a load capacity of about 785 pounds at 60 PSI. When selecting tires for smaller trailers, it is best to consider the tires load capacity in conjunction with the rim diameter.

A higher load capacity tire with 4-ply construction, such as the 5.30-12, can handle more weight without causing damage to the tire. The 5.30-12 tire size has a total diameter of 21.8 inches and a load capacity of about 1,045 pounds at 80 PSI.

13 Inches and Above

Trailers that require 13 inches and above rims are larger trailers like car haulers, horse trailers, and flatbed trailers. The most common tire size for these trailers is ST205/75R15, which has a total diameter of 27.1 inches and a load capacity of about 1,820 pounds at 50 PSI.

If you are looking to upgrade to a larger tire size, the ST225/75R15 could be a great option. It has a total diameter of 28.3 inches and a load capacity of about 2,540 pounds at 65 PSI.

This larger tire size offers better stability, improved fuel efficiency, and a smoother ride.

Deciphering Tire Codes

Service Type

The first letter on the tire code specifies the service type of the tire. P stands for passenger tires, and they are suitable for personal vehicles.

LT stands for light truck tires, and they have higher load capacities and are ideal for larger vehicles like SUVs, vans, and trucks. T stands for temporary spare tires, which are smaller in size, compact, and can only be used for limited distances.

TS stands for trailer special tires, which are specially designed for use on trailers.


The section width of a tire is spelled out in millimeters and is the measurement of the tire from sidewall to sidewall. The section width of a tire can be used to estimate how wide the tire is when it is mounted on a rim.

Aspect Ratio

The aspect ratio of a tire is represented as a percentage and is the ratio between the height of the tire and its section width. A lower profile tire has a lower aspect ratio, which means it has a lower sidewall height and a wider tread.

A higher profile tire has a higher aspect ratio, which means it has a taller sidewall and a narrower tread.


The construction of a tire refers to the materials and method used to make the tire. Radial tires are the most common tire construction and are characterized by the layers of cords that are oriented at 90 degrees to the direction of the travel.

They offer better fuel economy and a smoother ride compared to cross-ply or bias-ply tires, which are less common nowadays.

Rim Size

The rim diameter is the measurement of the tire seat diameter that the tire fits onto. The rim size varies depending on the size of the tire, and it is essential to ensure that the tire fits precisely onto the rim.

Load Index

The load index refers to the maximum weight that each tire can support. The load index of a tire should be more than the weight of the trailer plus 15% safety margin.

Speed Rating

The speed rating indicates the maximum speed at which the tire is capable of operating at a load specified by the load index. The speed rating is represented by a letter, with the letter S being the minimum requirement for trailer tires.

Load Range

The load range index refers to the tire’s maximum load capacity and its ability to withstand pressure and stress. In general, a higher load range index means a higher maximum load capacity, and it is important to consider the weight of the trailer when selecting a tire with the appropriate load range rating.


Choosing the perfect tire for your trailer requires you to consider important factors like the rim diameter, tire size, load capacity, and construction. Understanding tire codes and deciphering them can help take the guesswork out of the selection process and ensure you get the best fit.

Trailers come in various sizes, and with the right tire, you can optimize your trailers performance and safety. Choosing the right tire for your trailer is crucial to ensure that you are safe on the road and that your trailer performs well.

There are different trailer tire sizes and tire codes to decipher for selecting the perfect tire. But there are also many tire extras available that can make a big difference in your trailers performance and safety.

Additionally, utilizing additional charts like load range charts, speed rating charts, and tire load index charts can help you make an informed decision.

Importance of Special Features

Tire extras are designed to enhance your trailers safety and performance. One crucial feature to consider is the extra ply rating.

Ply rating refers to the number of layers of fabric and rubber inside the tire. A higher ply rating results in a stronger tire, which can withstand more pressure, making it less prone to punctures and blowouts.

Another important feature is the steel belt. Steel belted tires usually have a stronger construction than their non-steel belted counterparts, and they can handle heavier loads and are more puncture-resistant.

The type of tire pattern can also impact your trailers performance. Radial and bias-ply tires have different tread patterns, which can affect handling, fuel efficiency, and durability.

Radial tires have a smoother and flatter tread, which means they offer better fuel economy and a smoother ride. Bias-ply tires, on the other hand, have a stiffer sidewall, which provides better load-carrying capacity and shock absorption.

The availability of tire extras can also include warranties and guarantees. It is beneficial to consider brands that offer warranties to ensure that you receive the best customer service and support.

Importance of Additional Charts

Load Range Chart

A load range chart is a useful tool when selecting the right tire as it provides the minimum and maximum load-carrying capacity of each tire in a specific range. This chart helps you to choose the right tire according to your trailers weight.

Always ensure that the tires chosen have a higher load-carrying capacity than your trailer weight.

Speed Rating Chart

A speed rating chart indicates the maximum speed capability of each tire, represented by a letter. The higher the speed rating, the better the tire’s performance at higher speeds.

Speed limits vary by state, but even the fastest speed limits typically fall well below maximum speed rating of typical ST tires, making it important to select tires with an adequate speed rating. Choosing the wrong speed ratings can lead to problems like excessive heat in the tire, which increases the chances of tire failure.


Load Index Chart

The tire load index chart is an essential tool when selecting tires. Each tire’s load index specifies the maximum weight it can support at a specific PSI.

Before selecting a tire, it is crucial to consult this chart to ensure that the tires maximum carrying capacity exceeds your trailers weight.

Final Thoughts

Choosing the right tire for your trailer is crucial, but with the availability of trailer tire size charts, tire codes, and additional charts like load range, speed rating, and tire load index, it doesn’t have to be difficult. Additionally, don’t overlook the importance of special features and extras like extra ply rating, steel belt, and tread patterns when making your tire selection.

It is crucial to perform due diligence and select the appropriate tire and features to improve your trailers performance and, most importantly – your safety. In conclusion, choosing the right trailer tire size and decoding tire codes are only the beginning of ensuring your trailers optimal performance and safety.

Attention to extras like ply rating, steel belts, and tread patterns improve overall handling and reduce the risk of blowouts or punctures. Utilizing additional resources such as load range, speed rating, and tire load index charts further assist in selecting the ideal tire for your particular trailer.

With these points in mind, you can confidently select a tire that suits your needs and helps keep you and your trailer secure as you hit the road. FAQs:

Q: How do I determine the properly-sized tire for my trailer?

A: The trailer owner’s manual can provide guidance for selecting the right tire size or, alternatively, consult a tire sizing chart and ensure the tire closely aligns with the manufacturers recommendation. Q: How do I check my tires load capacity?

A: Refer to the tire’s side wall to understand the tire’s load capacity. The tire’s load-carrying capacity increases with a higher ply rating.

Q: How does speed rating affect my tire choice? A: A tires speed rating can impact its overall performance, and it is recommended to purchase a tire with a speed rating that exceeds the maximum speed you are likely to encounter almost all of the time.

Q: Are warranties/guarantees important when selecting tires? A: Yes, selecting a tire with a warranty can be essential in ensuring that you receive the best customer service and support in the event of an issue.

Q: What makes radial and bias-ply tires different? A: Bias-ply tires have a stiffer sidewall, providing better load-carrying capacity and shock absorption, while radial tires have a smoother flatter tread, offering better fuel economy and a smoother ride.

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