What PSI For Trailer Tires? | Cold Pressure Done Right

Most trailer tires should be set to the cold pressure on the trailer placard, then matched to tire size, load range, and real trailer weight.

A small utility trailer on load range C tires may want 50 PSI cold. A travel trailer on load range E tires may call for 80 PSI cold.

Guessing is what gets people in trouble. Too little air builds heat and wears the shoulders. Too much can make the trailer hop over rough pavement and wear the center of the tread. The clean answer starts with the trailer maker’s placard, then gets checked against the tire itself and the load you’re asking it to carry.

What PSI For Trailer Tires? Start With Cold Pressure

The first number to trust is the cold inflation pressure listed on the trailer’s certification label or tire placard. That label was picked around the axle rating, tire size, and factory setup. NHTSA’s tire safety guidance says the proper pressure is the vehicle maker’s recommended pressure checked when the tire is cold.

Cold means the trailer has been parked long enough for the tires to settle back to air temperature. If you stop after an hour on the road, the pressure will read higher. That rise is normal. Bleeding air from a hot tire often leaves you low once the tire cools again.

Placard, sidewall, and load range

Three markings matter:

• Trailer placard: the factory cold PSI for the trailer as built.
• Tire sidewall: the tire’s size, load range, and max load at a stated cold PSI.
• Load range: the pressure band the tire was built around, such as C, D, E, F, or G.

On many ST trailer tires, the sidewall pressure lines up with the pressure needed for the tire to carry its full rated load. That does not mean every trailer should be aired to the same figure. If the placard is present and readable, start there. If the placard is gone, use the tire maker’s load table and the loaded axle weight.

If The Label Is Missing

Don’t just copy the PSI from a neighbor’s trailer or an old forum post. Match the tire size and load range on your sidewall, then verify the weight on the axle. One tire size can come in more than one load range, and each version can want a different cold PSI.

Match PSI To The Load On The Trailer

If you want a sharper number for your own setup, weigh the trailer when it’s loaded the way you actually tow it. Water tanks, tools, generators, spare parts, and tongue weight can swing the answer more than most owners expect. A trailer that looks half full can still be heavy on one side or one axle.

A simple method works well:

1. Load the trailer for a real trip.
2. Get axle weights on a public scale.
3. Use the heavier side of an axle as your working number if you can get side-to-side weights.
4. Match that weight to the tire maker’s load table.
5. Set all tires on the same axle to the same cold PSI.

You don’t want one tire on an axle doing more work than the mate beside it. Michelin’s advice on weighing a trailer and matching pressure to load follows that same logic: weigh the setup loaded, then use the maker’s data book or table to pick the cold inflation needed.

If you can’t get to a scale, stay with the placard number. That is safer than guessing low because the trailer “looks empty.” Underinflation is a classic trailer-tire killer.

When Full Placard Pressure Makes Sense

Backing off pressure rarely helps when the trailer sees changing loads or long highway runs. Full cold placard pressure is often the safer play for:

• Travel trailers loaded close to gross weight.
• Cargo trailers that carry different loads week to week.
• Boat trailers that sit for long stretches, then run at highway speed.
• Any trailer with ST tires and no scale data.

Common Trailer Tire PSI By Type And Load Range

You’ll see the biggest PSI swings when the tire size stays close but the load range changes. Use this table as a working baseline, not a blind rule.

Tire marking or setup	Common cold PSI	Where it often shows up
ST load range B	35 PSI	Light boat and small utility trailers
ST load range C	50 PSI	Single-axle cargo and equipment trailers
ST load range D	65 PSI	Heavier utility and tandem trailers
ST load range E	80 PSI	Travel trailers, car haulers, enclosed cargo
ST load range F	95 PSI	Heavier RV and equipment trailers
ST load range G	110 PSI	Large fifth-wheel and heavy commercial trailer use
LT tire used on a trailer	Varies by size and load table	Some custom, off-road, or mixed-use builds
Bias-ply trailer tire	Usually follows sidewall rating	Older farm, boat, and light equipment trailers

A 15-inch trailer tire can be 50 PSI in one version and 80 PSI in another.

Signs Your Trailer Tire Pressure Is Off

Tires talk before they fail. The wear pattern, the way the trailer tracks, and the heat in the sidewall can tell you a lot. Spotting those clues early is often the difference between a cheap fix and a shoulder-side mess.

Pressure also shifts with weather. A handy shop rule is that tire pressure moves around 1 to 2 PSI for every 10 degrees Fahrenheit change in air temperature. That’s why a trailer set in July can read low on the first cold snap of fall.

What you notice	What it points to	What to do next
Shoulders wearing faster than center	Pressure may be too low for the load	Check cold PSI, load, and any slow leak
Center wearing faster than edges	Pressure may be too high	Check placard and tire spec before lowering
Trailer feels squirmy or drags	One or more tires may be low	Measure all tires cold, not just one
One tire runs hotter than the rest	Low air, overload, or brake issue	Check pressure first, then inspect hub and brake
Cupping or patchy wear	Balance, suspension, or pressure issue	Inspect running gear and verify PSI
Bulge, crack, or repeated air loss	Tire may be unsafe to tow on	Replace or have it inspected before the next trip

Hot Tire Checks On The Road

If you must check mid-trip, use the reading as a warning flag, not a final setting. A hot tire that is lower than its mates may be losing air. A hot tire that is higher than the rest may be carrying more load or may have started from a different cold pressure. Reset the tires when they are cold.

Cold Tire Routine Before You Tow

A five-minute routine beats a roadside tire swap.

1. Check all trailer tires before the day’s first move.
2. Use the same gauge each time so your readings stay consistent.
3. Set pressure to the placard or the tire maker’s load table number.
4. Check the spare too.
5. Scan the tread and sidewalls for nails, bulges, weather cracks, and cuts.
6. Recheck after long storage or a sharp weather swing.

If your trailer has a tire pressure monitoring system, treat it like an alarm. It can warn you after pressure drops. It does not replace a cold gauge check before a trip.

Mistakes That Shorten Trailer Tire Life

The same errors show up again and again:

• Using the tow vehicle’s door-jamb PSI instead of the trailer placard.
• Mixing tire sizes or load ranges on the same axle.
• Running old tires with plenty of tread but cracked sidewalls.
• Lowering pressure for a softer ride on the highway.
• Ignoring a trailer that leans to one side because it still tows straight.
• Loading heavy gear on one side and never checking axle weight.

Trailer tires sit, age, and then get asked to run loaded for hours. Good air-pressure habits help them run cooler and track straighter.

Pick The Right PSI With Confidence

Start with the trailer placard. Read the tire size and load range. Check pressure cold. Then, if you want a sharper number, weigh the loaded trailer and match the result to the tire maker’s chart.

So what PSI should your trailer tires run? Whatever the placard or load table says when the tires are cold and the trailer is loaded the way you tow it. For many trailers that lands at 50, 65, 80, 95, or 110 PSI. The right answer is tied to your tire, your axle rating, and your real load.