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Trailer Tires 101

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Trailer Tires 101

It’s important to pick the right trailer tire for your haul in order to avoid the worst possible outcome on the road: a tire blowout. Follow along with this guide to make sure that your precious cargo gets to your destination safely. Your choice of trailer tire depends on the weight of the load, size of your trailer, mileage, and other variables. We’ll help you make that informed choice. 

 

What is an ST tire?

ST on a tire stands for “Special Trailer.” As their name suggests, ST tires are specifically designed for trailer use. An ST tire should only be used on car, boat, or utility trailers and are not for passenger use. They have the durability to haul heavy loads and cross long distances.  

 

Why to Use ST Tires

ST tires, designated for trailer use, are the wisest choice for your hauling needs. Passenger tires are not made for heavy loads and will bend excessively and overheat. Light truck (LT) tires may be suitable for your heavy load, but offer a stiff ride and aren’t actually made for trailers. While they may be used, they might not be the best option for your personal trailer. ST tires, however, are specifically designed to maneuver at high speeds for long distances and haul heavy loads. With more durability than passenger tires, ST tires have a robust construction that can withstand more vertical weight because of its thicker sidewalls. 

 

 

Advantages of ST Tires

ST tires exist because they can haul what normal passenger tires don’t have the capacity to. They have better tread for hauling and better puncture resistance.

A normal passenger tire would not be efficient at handling heavy loads while also maintaining a high speed. The thicker and stiffer sidewalls of an ST tire are to your advantage when hauling your trailer/camper/boat because they reduce swaying when traveling down the road at high speeds.

 

Choosing Trailer Tires

When choosing a trailer tire model, account for the following factors: the size of the load you will be hauling, the distance traveling, and the types of roads you’ll be driving across. Are you hauling a trailer halfway across the country? Or are you launching your boat off at your local marina? Take these factors into consideration so you can pick the tires most suitable for your use.

 

  1. 1. Load Rating: The trailer tire load range indicates how capable the tires are to pull heavy loads like boats, campers, livestock or even other cars. Referring to a trailer tire load range chart can help you determine the correct rating for the weight of your trailer.

 

  1. 2. Speed Rating: The trailer tire speed rating is conveyed through a code. A tire rated L can be operated up to 75 mph while a tire rated M can be operated up to 81mph.

 

  1. 3. Size of Trailer: Different size tires are made to fit each specific trailer. 

 

  1. 4. Your budget: Determine the highest quality option in your price range.

 

Types of Trailer Tires 

There are two main types of trailer tires: Bias or Radial. You'll need to decide which is right for your trailer.

Bias tires perform better on straight stretches but they don’t do well on winding roads. They can haul heavy loads, but they’re also susceptible to abrasion and heat because of the load pressure on the tires. Bias tires have the benefit of being the less expensive option of the two. 

Radial tires have better control on curves than bias tires do and provide a smoother, quieter ride. They also run cooler because of their steel mesh framework. Radial tires are more expensive because of their wider footprint which actually yields even tread wear and gives the tire better tread life and better puncture resistance. 

*It should be noted that if you’re looking to replace your current tires on a trailer, you should never replace radial tires with bias-ply tires.

 

After determining whether you need a bias or radial tire, you’re ready to determine your load range, use this simple calculation: Divide the weight of the trailer loaded, by the number of tires that will be sharing that load. Find a tire with a load range that exceeds that number.

From there you’ll need to determine the class of tire that is right for your trailer. Class systems are used to sort tires by their load range: the weight of the trailer and its contents.

 

 

Class ratings fall under the category B, C, D, or E; B being the lightest and C being the heaviest. Many boat trailer tires fall under the C or D classification. Utility trailers also do best with tires in the D range. Cargo trailer tires should use tires with a C load range. Large travel trailers use tires with an E class rating. As a rule, if you’re replacing the tires on your trailer, make sure the load capacity number, located on the tire’s sidewall, matches the load capacity number of your previous set. 

Be smart about the tires you are using for your trailer. The last thing you want to happen on the road is a tire blowout! 

 

What is the best trailer tire?

The best trailer tire for your haul and vehicle is going to be dependent on the load capacity and Gross Vehicle Weight Rating. GVWR (Gross Vehicle Weight Rating) is the total safe weight of your vehicle. This accounts for the curb weight (the weight of your vehicle when empty), combined weight of your passengers, cargo load, other additional accessories added to the vehicle, and even the amount of fuel. It’s important you determine these measurements before you select a tire. It can be overwhelming to pick the right trailer tire so we’ve included a few recommendations.  

 

The Carlisle Radial Trail HD. This radial tire is “designed with a unique tread pattern that wears evenly over time.” This tire has the ability to withstand high heat, is puncture resistant, and has low rolling resistance: perfect for boats, cargo, horse and livestock, RV, towable utility, and specialty trailers. This tire comes in a variety of sizes and load ratings from C to F.

The Goodyear Endurance Trailer Tire. This tire is built using Durawall® technology and scuff guard sidewall protection which allows it to withstand wear and resist punctures and helps to extend its lifespan. The Endurance comes in a variety of sizes for all your hauling needs, whether for work or for play.

The Hankook Vantra. This is actually not an ST tire, but an LT tire meaning it is meant for light truck usage. This tire is also optimized for mileage longevity and maximum performance in the rain. This tire is ideal for boat, cargo, RV, and other trailers to withstand long hauls.


 

What PSI should my trailer tires be at?

Your tires’ load capacity takes into account the specific tire pressure your trailer tires should contain to carry your load. If the tire is below the max psi, you reduce the load capacity of the trailer. On the contrary, if the tire is above the max psi, you risk a blowout due to high pressure in your tires. 

We recommend that all trailer tires be inflated to the max psi stated on the sidewall of the tire. This will ensure that the weight rating handles its maximum load capacity. If you have a lower air pressure for a light load, it may improve the ride of the trailer but the carrying capacity of the load is reduced significantly. If a heavier load is put on the trailer without using the recommended air pressure, the sidewall of the tire could cause a blowout. 

Lastly, weather is also a determinate of the tire’s psi. When it’s cold, you’ll need to pay extra attention to your tire’s psi and make sure to inflate them to their max psi. This way, you’ll get full capacity at the max psi since there is less flex on the sidewall. Therefore, you’ll get better gas mileage. 

 

Do trailer tires need to be balanced?

You should rotate and balance your trailer tires regularly,  as often as you would your personal vehicle. Rotating your tires side to side (for single axle trailers) will help even out irregular treadwear, extending the overall lifetime of your tires. For double axle trailers, an X rotation is recommended. 

If you notice irregular wear patterns developing, it’s recommended to get your tires checked by a trusted technician for service or possible replacement. 

 

How long do trailer tires last?

The built-in tread wear indicator bars are there to help you realize when it’s time to replace your trailer’s tires.  You can check this by using a tread depth gauge or by placing a penny in the tread with Lincoln’s head upside down and facing you. If you see the top of his head, it’s time to buy new tires. Keep 2/32” as a general rule of thumb for the tire. 

 

How to Store Trailer Tires

For short-term storage, if there isn’t the opportunity to store your trailer tires inside, you should at the very least park your trailer in the shade. For better protection, you should cover them up with wheel covers, or a tarp is equally as effective. 

For extended periods of time, move your trailer inside. When the trailer is parked outside, pressure from the weight of the trailer for a long period of time on hot asphalt begins to cause damage to your tires and can cause dry rot.

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