Trailer Tires, marked by the classification ST, are tires intended for use on a trailer. They are a different type of tire than your average car and have different requirements. Despite this, many people will make the mistake of putting a car tire on a trailer.
This is unsafe, and can lead to a blowout. If you’re towing a heavy load at the time, this can cause a fatal traffic accident.
In this article, we’re going to do a basic rundown of how to keep safe with your trailer tires, and keep them lasting longer.
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What makes trailer tires different?
The tires on your vehicle are designed with a vehicle in mind. They steer, transmit power from engine to road, and maintain a long tread life over an extended period of active wear.
Trailer tires, or ST tires, have a design focused on other factors. They tend to have thicker or more plies for carrying heavier loads. The side walls are thicker too – and include special compounds to help stiffen them.
In fact, most of the tire design focuses on that load carrying capacity. Trailer tires are narrower than car tires to help strengthen the side walls, for example. A car’s tire is flatter and wider, allowing them to keep traction while swerving to avoid a wreck.
Putting a car tire on a trailer may seem like an easy fix – but it is a risky situation. Always have an inflated spare or two when towing things with your trailer.
Choosing the right kind: Bias or Radial ply
When purchasing tires for your trailer, you may come across these two options. They each have their strengths, and the kind you buy should depend on your use.
It’s VERY important that whatever kind you choose, you match all tires on your trailer as the same type – Bias or Radial.
Bias Ply ST tires are designed with heavy load capacity and low usage in mind. Their sidewalls are strengthened and stiffened even further, offering less sway for heavy loads.
In tires, plies are the layers of material that form the casing
The plies in bias ply tires are laid down in a 30-45 degree angle to the center of the tire. This emphasizes sidewall strength, allowing them to take heavier loads than a radial.
Bias ply tires are often cheaper, but in return they provide less mileage than radials before their tread wears out.
Most trailer tires wear out from age well before tread wear becomes an issue. If the goal of the tires is a heavy load or infrequent use, it may still be better to buy bias ply for your trailer.
They last roughly 12,000 miles over a 3-5 year life span. If you only break the trailer out once or twice a year, bias ply should suit your purpose at a lower price.
Unlike bias ply, radials have constant use in mind during their construction. Many trailers even come equipped with radial ply tires straight out of the factory.
What sets them apart is that radial ply trailer tires are built in a similar way to radial car tires. In both cases, the plies run at a 90 degree angle to the center-line of tread, and are then strengthened with steel mesh belts. They tend to be more expensive, but are better for frequent use.
Radials offer a smoother and quieter ride, with a wider footprint design than bias ply. They tend to also have better fuel economy, and do better on curves. Overall, if a trailer is seeing over 5,000 miles a year – ST Radials may be a better option.
Radials last around 40,000 miles, though still only have a 3-5 year life span. If the trailer is going to see frequent use, a radial design is the stronger option – even at the higher price point.
Safety basics when replacing trailer tires
When replacing tires on a trailer, always ensure that both tires on the same axle are of similar tread depth. If one tire is a brand new replacement for a flat, and the other tire is a year and a half old – go ahead and replace both.
Otherwise, you run the risk of unevenly wearing down your new tire.
Always check your trailer’s requirements when purchasing a new tire. These requirements can be found on the certification label or the owner’s manual, and they are not suggestions. If ever in doubt, double check the certification label or owner’s manual. Check out the best trailer tires in order to avoid purchasing the wrong set.
Never mix bias ply and radial ply on a trailer. They are different designs, and mixing them up can affect how the weight is distributed across the trailer. The consequences of this can be a fatal blowout.
Keeping your trailer tires maintained and lasting longer
Now that the replacements have been decided on, here are a few tips on how to maintain those tires.
If the trailer sees frequent periods of disuse sitting in storage, it’s important to guard the tires against sunlight. Additionally, move it at least once every three months to prevent flat spots.
When you move the trailer, use chalk to mark along the bottom of the tire. Try and park it with the chalk mark at a 90 degree angle to where it was before to cut the risk of flat spot and damages
If storing a trailer indoors – don’t run ozone producing devices, such as generators, in the same building. The chemicals in the exhaust can cause long term damage to the exterior of the tires
Every time the trailer is about to see use, follow this basic safety checklist:
- Check tire for any cracks or deterioration in the rubber
- Check tire tread for uneven wear
- Check tire PSI – if it has changed by more than a few PSI since last check, there may be a leak
- Check date tire was put on trailer
By taking these precautions, you can make sure that your trailer tires last as long as possible. Even still, once the tire hits that 3 year mark – be careful and start thinking about replacements.
Most of the damage done to trailer tires comes from the oxygen in the tire, and is invisible to the naked eye. A trailer tire should always be replaced after five years, at most.
To push them that long, make sure you choose the tire type that suits your trailer needs. If you only use your trailer a few times a year for short trips, Bias ply may be a better fit. But if your trailer sees service often, driving over 5,000 miles per year, Radials are worth the price difference.
When storing your trailer, be sure that you do so in a way that won’t harm those new tires.
Finally, follow all manufacturer’s guidelines on use and weight capacity. Keep the tire inflated according to those guidelines, and only put on tires that meet your trailer’s requirements.
By doing this, you can ensure that your trailer tires live up to their maximum potential.