When Should You Replace Trailer Tires? Follow This Safety Checklist

I’m the type who can almost never throw something out.

I wear my shoes until they have holes. I reuse tea bags. I keep my phone until the day it stops turning on.

But when it comes to trailer tires, I’m a different person.

Old or worn tires pose a substantial danger on the road. They can lead to blowouts, a terrifying experience for you, your horses if you’re carrying them, and other drivers.

So it’s vital to know when to replace trailer tires. We’ll walk you through a checklist to determine whether yours are ready for an upgrade.

But first, are you keeping your tires safe and strong day-to-day? Here’s how:

Quick Tips for Trailer Tire Longevity

  • Regularly clean out pieces of debris or foreign objects that may have gotten lodged in your tires.
  • Fill tires to the maximum PSI (which is always listed on the sidewall of the tire) when the tires are cold, before you travel. Check your tires’ pressure levels, including the spare!
  • Check tires’ load range (also listed on the sidewall) to make sure you’re not putting more weight in your trailer than the tires can handle. Remember to calculate the total weight including the trailer itself, or ask a trailer professional to confirm that you have the appropriate tire size and load range on your trailer.
  • Make sure your tire valves have valve caps.
  • As always, drive slowly and keep an eye out for foreign objects or potholes in the road. If you can’t avoid a pothole, drive over it as slowly as you can. Try to avoid rolling against the curb when parking.

How to Know if It’s Time to Replace Trailer Tires

1. Confirm That Your Tire Matches Your Trailer

Check the side of your tire for the letters ST.

LT tires are designed for “light truck” use and P are designated for “passenger” cars, while ST tires are designed specifically for use on a trailer.

As US Rider explains, this distinction has to do with how rough of a ride they can take. LT tires are meant to accompany vehicles with a sophisticated suspension system to create a smooth ride. Horse trailers don’t come with this type of suspension so they need ST tires, which can endure more bumps on the road.

2. Measure Your Tread Depth

Legally, your tires need to be replaced when they have 2/32” of remaining tread depth. The common piece of advice here is to insert a penny with Lincoln’s head facing downward into your tire’s tread groove–if part of Lincoln’s head is still covered, you have enough tread depth.

3. Check for Uneven Tread Wearing

Make sure the tread isn’t worn just on the outer edges of the tires or just down the center. Uneven tread wearing can indicate a number of safety issues with your tires or trailer:

  • Overinflation (worn in the center) or underinflation (worn on the outer edges)
  • A bent axle or spindle
  • Axle alignment problems
  • Hauling weight that exceeds the trailer’s load capacity

Check out this article for an in-depth discussion of those issues and how to diagnose or resolve them.

4. Get a Dry Rot Check

Moisture and heat are tires’ worst enemies. Over time, they can break down the tire rubber and cause dry rot.

Unfortunately, dry rot is not always easy to find. A tire that looks smooth and intact might be hiding dry rot within the sidewalls. So it’s important to get a professional check about once a year. A professional has special lighting tools and can flex and bend tires in a strategic way to reveal possible dry rot.

5. Consider Your Tire’s Age

Generally speaking, a tire’s lifespan is five years–whether it’s being used or not! Heavy use will of course reduce this lifespan, which is why it’s important to weigh your tire’s age along with the factors above.


Want ultimate peace of mind on the road? Contact Blue Ridge Trailers online or at (434) 985-4151 for a professional trailer and tire safety check.

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