Trailer Tires in Summer Heat: Pressure, Age, and Blowouts

July heat is hard on trailer tires. Hot pavement, heavy loads, and long highway runs all add up, and a blown trailer tire is one of the most common reasons people end up on the shoulder. The good news: most tire failures give you warning signs ahead of time if you know where to look.

Why trailer tires are different

Trailer tires aren't the same as the tires on your truck. Many trailers use ST (Special Trailer) tires, which are built with stiffer sidewalls to carry heavy loads and resist sway. They're designed to be pulled, not to steer or drive.

That also means a few things work differently:

• Speed ratings are often lower than car tires. Check the sidewall. Some trailer tires are rated for 65 mph, others higher. Don't assume.
• Trailer tires carry a lot of weight on a small footprint, so pressure matters even more.
• Trailer tires often sit for weeks or months between trips, which can age them faster.

Check pressure the right way

Underinflation is the number one cause of trailer tire failures. A soft tire flexes more, builds up heat, and can come apart at highway speed.

• Check pressure cold, before you drive. Tires heat up as you drive, and a hot reading will look higher than it really is.
• Inflate to the pressure listed on the tire sidewall or the trailer's VIN/load sticker, not the number on your truck's door.
• Don't let air out of hot tires. It's normal for pressure to go up as tires warm.
• Use a good gauge. Cheap pencil gauges can be off by several PSI.

Make it part of your pre-trip checklist every time.

How old are your tires?

Trailer tires can look fine and still be too old. Rubber breaks down over time from sun, heat, and ozone, even if the tread is deep.

On the sidewall, look for the letters DOT followed by a code. The last four digits tell you when the tire was made: the first two are the week and the last two are the year. For example, "2422" means the 24th week of 2022.

Many tire makers recommend replacing trailer tires after about five to six years, no matter how they look. Check your tire manufacturer's guidance, and replace sooner if you see cracking.

Warning signs to look for

Walk around the trailer and look closely at each tire:

• Cracks in the sidewall or between the tread blocks (often called "dry rot")
• Bulges or bubbles in the sidewall, which mean internal damage. Replace it.
• Uneven wear, like one edge worn more than the other. This can point to an axle alignment problem, a bent axle, or an overloaded side.
• Cupping or flat spots, which can come from hard braking or from sitting in one spot too long
• Cuts, punctures, or exposed cords

Don't overload

Every tire has a maximum load printed on the sidewall. Multiply that by the number of tires on the trailer, and that's the most the tires can carry. The trailer's GVWR is set with this in mind, which is one more reason to stay under it. See our guide on towing capacity and payload.

Summer driving tips

• Slow down a little. Heat builds faster at higher speeds. A few miles per hour slower can make a real difference on a hot day.
• Check tires at every stop. Look at each one and carefully feel the tread. If one is much hotter than the others, it may be low on air, or the hub may have a bearing problem. Our wheel bearing guide explains what to look for.
• Carry a spare that's inflated and in good shape, plus a jack and lug wrench that fit the trailer.
• Avoid curbs when turning. Trailer tires take a shortcut through corners and hit curbs more often than you think.

If a tire blows

Don't slam on the brakes. Hold the wheel firmly, ease off the gas, and let the rig slow down in a straight line. When you're under control, signal and pull fully off the road. Use your hazard lights, and change the tire only where you have room to work away from traffic.

Small habit, big payoff

Checking pressure takes two minutes. Reading the date code takes ten seconds. Those two habits prevent most trailer tire trouble. Follow us on Facebook for a new towing tip every week, and see our Rental Fleet page for our two rental trailers.