Trailer Tire Size Complete Guide

Do you own a trailer? If so, you probably know that having the right tires is important for keeping your trailer safe and secure while you’re driving. But with all the different tire sizes available, it can be hard to choose the right ones. That’s why we’re here to help!

Trailer tires come in a variety of sizes, but they generally fall into two distinct categories – those that are 12 inches or less, and those that measure 13 inches or more.

In this guide, I’m going to talk about trailer tire sizes. We’ll explain what you need to know when choosing tires for your trailer, including how the size can impact things like how well it handles and how much weight it can carry. 

Standard Trailer Tire Size

When selecting trailer tires, the first step is to determine the diameter of the rim. By doing this, you can narrow down your options and focus on finding the tires that will work best with your specific rim size.

As I’ve mentioned before, trailer tires come in two groups – ones that are smaller than 12 inches and ones that are bigger than 13 inches. To make it easier for you to pick the right tires, we’ve made a chart that shows all the different tire sizes, how wide the rims should be, and how much weight each tire size can handle. With this helpful chart, you’ll have all the information you need to pick the best tires for your trailer.

8 – 9 – 10 – 12 – Inch Trailer Tire Size

Rim Size (inches)Tire Size (inches)Rim Width (inches)Load CapacityTotal Diameter (inches)
84.80/4.00-83-3/4 inchB: 590 lbs @ 60 psiC: 760 lbs @ 90 psi16.1 inches
85.70-83-3/4 inchB: 715 lbs @ 50 psiC: 910 lbs @ 75 psiD: 1,075 lbs @ 100 psi18.1 inches
8165/65-85-3/8 inchC: 800 lbs @ 70 psi16.5 inches
8215/60-87 inchC: 935 lbs @ 50 psiD: 1,165 lbs @ 70 psi18.3 inches
96.90/6.00-94-1/2 inchC: 1298 lbs @ 60 psi21.1 inches
10205/50-106 inchB: 665 lbs @ 30 psi18.3 inches
10205/65-106 inchB: 910 lbs @ 35 psiC: 1,100 lbs @ 50 psiD: 1,330 lbs @ 70 psiE: 1,650 lbs @ 90 psi20.5 inches
124.80-124 inchB: 785 lbs @ 60 psiC: 990 lbs @ 90 psi20.5 inches
125.30-124 inchB: 840 lbs @ 55 psiC: 1,045 lbs @ 80 psiD: 1,250 lbs @ 105 psi21.9 inches
12145/80-124 inchD: 1,220 lbs @ 65 psiE: 1,520 lbs @ 80 psi21.3 inches

13 – 14 – 15 – 16 – 17.5 Inch Trailer Tire Size

Rim Size (Diameter in Inches)Metric/Tire size (Inches)Rim Width Range (Inches)Load CapacityTotal Diameter (Inches)
13175/80-134-1/2, 5, 5-1/2B: 1,100 lbs @ 35 psiC: 1,360 lbs @ 50 psiD: 1,610 lbs @ 65 psi24.1 inches
13185/80-134-1/2, 5, 5-1/2C: 1,480 lbs @ 50 psiD: 1,725 lbs @ 65 psi24.4 inches
14205/75-145, 5-1/2, 6, 6-1/2B: 1,430 lbs @ 35 psiC: 1,760 lbs @ 50 psiD: 2,100 lbs @ 65 psi26.3 inches
14215/75-145-1/2, 6, 6-1/2, 7C: 1,870 lbs @ 50 psi26.7 inches
14.58-14.5MH6 inchE: 2,540 lbs @ 85 psiG: 3,070 lbs @ 116 psi27.7 inches
15205/75-155, 5-1/2, 6, 6-1/2B: 1,480 lbs @ 35 psiC: 1,820 lbs @ 50 psiD: 2,150 lbs @ 65 psi27.1 inches
15225/75-155, 6, 6-1/2, 7C: 2,150 lbs @ 50 psiD: 2,540 lbs @ 65 psiE: 2,961 lbs @ 90 psi28.4 inches
157.00-15LT5, 5-1/2, 6E: 2,403 lbs @ 70 psi29.4 inches
16235/80-166, 6-1/2, 7, 7-1/2D: 3,000 lbs @ 65 psiE: 3,500 lbs @ 90 psi30.9 inches
16235/85-166, 6-1/2, 7, 7-1/2E: 3,640 lbs @ 95 psiF: 3,960 lbs @ 110 psi31.6 inches
167.50-16LT6D: 2,590 lbs @ 60 psiE: 2,926 lbs @ 75 psiF: 3,168 lbs @ 85 psi31.8 inches
17.5215/75-17.56-3/4 inchH (single): 4,805 lbs @ 123 psiH (dual): 4,540 lbs @ 123 psi30.2 inches

How To Read a Trailer Tire Codes?

read code on tires

You might notice a lot of confusing symbols and codes when you look at the writing on the side of a tire. You might also see that the codes on one vehicle’s tires can be completely different from another’s. 

You may come across a trailer tire with the designation “LT 215/75 R15 106Q D1 BSW” imprinted on its sidewall.

These symbols represent the following information:

[Service Type][Width]/[Aspect Ratio][Construction][Rim Diameter][Load Index][Speed Rating][Load Range][Extras]

Let’s examine each component.

Service Type

The service type of a tire refers to the type of vehicle it is designed to support. There are several service types, but for trailer tires, you only need to focus on three: P for passenger vehicles, LT for light trucks, and T or TS for trailers.


The next part of the tire code tells us the width of the tire in millimeters. This measurement is taken when the tire is filled up with air, but not yet put on a vehicle. It’s good to keep in mind that when the tire is holding up a trailer or vehicle, the width might be a little bit bigger, so it won’t be exactly the same as what’s written in the code.

Aspect Ratio

The next part of the tire code gives us information about the tire’s height and width relationship, without counting the wheel. For example, in the code “215/75 R15 106Q D1 BSW”, the “75”  indicates that the distance from the tread of the tire to the edge of the rim is 75% of the tire’s nominal width. This aspect ratio helps us understand how the tire will look in comparison to its width.


The construction of a tire refers to how it’s put together on the inside. When shopping for trailer tires, it’s crucial to check the construction code. The code “R” stands for radial, which is the type of tire that’s best for trailers. There’s another type of tire called bias ply, but it’s mainly used for commercial purposes, not for everyday trailers. By knowing the construction code, you’ll have a better understanding of what makes the tire strong and long-lasting.

Rim Size

When reading the code on your trailer tire, you’ll notice a number that represents the size of the inner rim that sits on the wheel. This number is called the tire seat diameter and it’s important to keep in mind when choosing a tire. But, it’s important to remember that this number doesn’t tell you anything about the width of the rim. The width of the rim is another key factor to consider when selecting a tire. So, don’t forget to think about both the tire seat diameter and rim width when making your decision!

Load Index

The load index lets us know how heavy a tire can carry. In our example, the “106” means the tire can carry a weight of 2094 pounds. It’s important to always make sure your tires can handle the weight they are carrying!

Speed Rating

This code lets us know the fastest speed that a tire can safely go. In the example tire, the code “Q” means it’s designed to handle speeds up to 100 mph.

Load Range

The final code is a bit more complicated, but don’t worry! You don’t need to understand it completely to choose the right tire. All you need to know is that it gives information about how much weight a tire can handle. But don’t worry, the Load Index that we talked about earlier is all you really need to keep in mind.


The final part of the tire code often referred to as the “Extras”, may not carry as much significance compared to the other sections as it doesn’t impact the tire’s performance. For instance, the code “BSW” in the example just indicates a “Black Side Wall”.

How to Measure Trailer Tire Size?

To measure the tire size for your trailer, you need to take into account the diameter, width, and aspect ratio. The diameter is the measurement of the tire from one sidewall to the other through the center.

The width refers to the tire’s width from sidewall to sidewall, while the aspect ratio indicates the tire’s height in relation to its width. By measuring these parameters accurately, you can determine the correct tire size for your trailer.


What is the standard trailer tire size?

The standard trailer tire size can vary depending on the type and size of the trailer. However, one common standard trailer tire size is ST205/75R15. This size is often used for smaller trailers and utility trailers.

How do I know my trailer tire size?

To determine your trailer tire size, you can check the sidewall of your existing tires. The size is usually displayed in a standardized format, such as ST205/75R15. The “ST” indicates a special trailer tire, followed by the width of the tire in millimeters (205), the aspect ratio (75), and the rim diameter in inches (15).

What is the size of a trailer rim?

The size of a trailer rim corresponds to the rim diameter. For example, if your trailer tire size is ST205/75R15, the rim size would be 15 inches.

Can I put 15-inch tires on my trailer?

Whether or not you can put 15-inch tires on your trailer depends on the specifications and requirements of your specific trailer. It is important to consult the manufacturer’s guidelines or the trailer’s documentation to ensure that 15-inch tires are compatible and safe for use. Using tires that are not recommended or approved for your trailer can affect its performance and safety.

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