Trailer Tire Pressure Chart: Correct PSI by Size, Load Range & Trailer Type
A practical, up-to-date guide for boat, utility, travel, and horse trailer owners who want safer towing and longer tire life.
Air pressure is the quiet make-or-break detail of towing. Carlisle’s trailer tire FAQ calls underinflation the number one cause of trailer tire failure, yet plenty of owners still guess, or copy the number from the pickup’s door-jamb sticker.
That shortcut causes trouble. A pickup may run at 35 psi, but trailer tires are a different animal. Their sidewalls are stiffer, their load ratings are higher, and their maximum pressures commonly sit at 50, 65, or 80 psi, and sometimes above 100.
This trailer tire pressure chart puts the numbers in one place: PSI by load range, tire size, and trailer type. It also explains how to read a sidewall and when a load-based table beats the maximum-pressure rule. The figures come from published load and inflation tables, and the sidewall on the actual tire always has the final word.
For most special trailer (ST) tires, the correct pressure is the maximum cold PSI printed on the sidewall, as long as it does not exceed the wheel’s rating or the trailer manufacturer’s placard. By load range, that works out to 35 psi (B), 50 psi (C), 65 psi (D), 80 psi (E), 95 psi (F), and 110 psi (G). Pressure must always be measured when the tires are cold.
Trailer Tire Pressure Chart by Load Range
Load range is a letter that describes how tough a tire is. It also sets the maximum cold pressure at which the tire carries its rated load. Discount Tire’s trailer guide points out that Load Range B is the lightest duty, supporting less than 1,000 lb at 35 psi, while C, D, and E cover most trailers on the road.
| Load range | Ply rating | Max cold PSI | Typical trailers |
|---|---|---|---|
| B | 4 | 35 psi | Light utility and small boat trailers |
| C | 6 | 50 psi | Boat, utility, and pop-up trailers |
| D | 8 | 65 psi | Mid-size boat, cargo, and travel trailers |
| E | 10 | 80 psi | Travel trailers, horse trailers, larger cargo trailers |
| F | 12 | 95 psi | Heavier travel trailers and fifth wheels |
| G | 14 | 110 psi | Heavy fifth wheels, large horse and equipment trailers |
Older bias-ply sizes such as 4.80-12 and 5.30-12 do not use the table above. A 4.80-12 Load Range B tire tops out at 60 psi, and Load Range C at 90 psi. The number on the sidewall is the only reliable guide.
How to Read a Trailer Tire Sidewall
Every ST tire prints its pressure rule on the rubber. A typical marking looks like this:
MAX LOAD 2830 LBS (1284 KG) AT 80 PSI (550 KPA) COLD
- ST: special trailer tire, built for towing only.
- 225: section width in millimeters.
- 75: sidewall height as a percentage of the width.
- R: radial construction. A “D” in that spot means diagonal bias-ply.
- 15: wheel diameter in inches.
- Load Range E: a 10-ply rating with an 80 psi maximum.
- 2,830 lbs at 80 psi cold: the capacity at maximum pressure. The word “cold” matters.
The four-digit DOT date code sits nearby. It shows the week and year of manufacture, so a code of 2523 means week 25 of 2023.
Trailer Tire Pressure Chart by Tire Size
Size and load range together decide the pressure and the weight a tire can carry. The table below lists popular trailer tire sizes with typical single-tire capacities at maximum cold pressure.
| Tire size | Load range | Max cold PSI | Max load per tire | Common on |
|---|---|---|---|---|
| 4.80-12 (bias) | B | 60 psi | 780–785 lb | Small utility and personal watercraft trailers |
| 4.80-12 (bias) | C | 90 psi | 990 lb | Small utility trailers |
| 5.30-12 (bias) | C | 80 psi | 1,045 lb | Utility and small boat trailers |
| ST175/80R13 | C | 50 psi | 1,360 lb | Boat and utility trailers |
| ST205/75R15 | C | 50 psi | 1,820 lb | Boat and utility trailers |
| ST205/75R15 | D | 65 psi | 2,150 lb | Boat and cargo trailers |
| ST225/75R15 | D | 65 psi | 2,540 lb | Travel and boat trailers |
| ST225/75R15 | E | 80 psi | 2,830 lb | Travel and larger boat trailers |
| ST235/80R16 | E | 80 psi | 3,420 lb | Travel trailers and fifth wheels |
| ST235/80R16 | G | 110 psi | 4,080 lb | Heavy fifth wheels and equipment trailers |
| ST235/85R16 | E | 80 psi | 3,640 lb | Horse trailers and heavy travel trailers |
Capacities are typical published values. Brands vary slightly, so the sidewall of the installed tire overrides this chart.
4.80-12 Trailer Tire Pressure Chart
The 4.80-12 is a bias-ply tire common on small utility trailers. It runs at 60 psi in Load Range B and 90 psi in Load Range C, and it carries roughly 780 to 990 lb depending on the range. Because its 20.5-inch diameter turns roughly 35 to 40 percent more revolutions per mile than a 15-inch ST225/75R15, a soft 4.80-12 heats up quickly on long highway runs.
ST205/75R15 and ST225/75R15 Pressure
These are the most common 15-inch trailer sizes. An ST205/75R15 in Load Range C carries 1,820 lb at 50 psi. Moving an ST225/75R15 from Load Range D to E lifts capacity from 2,540 lb to 2,830 lb, an increase of about 11 percent per tire, and raises maximum pressure from 65 to 80 psi.
ST235/80R16 Pressure
Heavier trailers usually step up to 16-inch tires. An ST235/80R16 carries 3,420 lb in Load Range E at 80 psi, and 4,080 lb in Load Range G at 110 psi, a jump of roughly 19 percent. More detail on this size is available in the ST235/80R16 trailer tire guide.
Max PSI vs. Load-Based Inflation: What Manufacturers Say
Trailer tire makers do not all give the same advice, and that confuses many owners. The table below shows how much weight two popular sizes can carry at different cold pressures. It is the same kind of load and inflation data published by brands such as Goodyear and Sailun.
| Cold PSI | ST225/75R15 | ST235/80R16 | Load range reached |
|---|---|---|---|
| 35 psi | 1,760 | 2,090 | B |
| 40 psi | 1,880 | 2,270 | – |
| 45 psi | 2,020 | 2,430 | – |
| 50 psi | 2,150 | 2,600 | C |
| 55 psi | 2,270 | 2,730 | – |
| 60 psi | 2,380 | 2,870 | – |
| 65 psi | 2,540 | 3,000 | D |
| 70 psi | 2,620 | 3,140 | – |
| 75 psi | 2,720 | 3,260 | – |
| 80 psi | 2,830 | 3,420 | E |
The key lesson is capacity. Dropping an ST225/75R15 from 80 psi to 50 psi cuts its rated load from 2,830 lb to 2,150 lb, a loss of about 24 percent. Air, not rubber, carries the weight.
The “Run Max PSI” Position
Carlisle’s FAQ tells owners to maintain the maximum PSI listed on the sidewall, measured cold and in the shade. Trailer-parts specialists such as etrailer agree: ST sidewalls are stiff, underinflation is the usual cause of failure, and few owners re-weigh before each trip. Maximum pressure is therefore the safest default, empty or full.
The “Inflate to the Load” Position
Goodyear and Sailun publish load-based charts for some ST tires. Supporters of this approach point out that a lightly loaded tire at full pressure can ride harshly and may wear the center of the tread. RV tire specialists who favor it still say to weigh each axle first and add a safety margin, commonly 15 to 25 percent. The pressure should also never fall below the trailer placard for the same tire size and load range.
A tandem-axle trailer weighs 7,000 lb loaded, so the average is 1,750 lb per tire. Adding a 15 percent margin gives about 2,010 lb. In the ST225/75R15 table, 45 psi supports 2,020 lb.
That 45 psi is the floor the math allows, not the target. Loads shift and tires run hot on summer highways, so the sidewall maximum stays the conservative default.
Trailer Tire Pressure by Trailer Type
Different trailers put tires under different stress. This comparison shows what each type usually runs and what to watch.
| Trailer type | Common sizes | Typical load range | Typical max PSI | Watch-outs |
|---|---|---|---|---|
| Boat trailer | 4.80-12, ST175/80R13, ST205/75R14 or R15 | B to D | 35–65 psi (bias 60) | Saltwater corrosion, long storage, slow leaks |
| Utility trailer | 4.80-12, 5.30-12, ST205/75R15 | B to D | 35–80 psi | Overloading, low wheel ratings |
| Travel trailer / RV | ST225/75R15, ST235/80R16 | D to G | 65–110 psi | Uneven weight, tire age, hidden blowouts |
| Horse trailer | ST or LT 235/85R16 | E to G | 80–110 psi | Shifting live load, heat, age |
Boat Trailer Tire Pressure Chart
Boat trailers often use small tires, such as an ST175/80R13 Load Range C rated for 1,360 lb at 50 psi. They also sit for weeks, and slow leaks add up quietly.
- Check pressure before every trip, not just at the start of the season.
- Rinse valve stems, wheels, and hubs with fresh water after saltwater launches.
- Match the load range to the loaded weight of the boat, motor, fuel, and gear, not the boat’s dry weight.
Utility Trailer Tire Pressure Chart
Utility trailers are the most likely to be overloaded, because a landscaping load of wet soil or stone weighs more than it looks. Small wheels also matter. Toyo’s load tables warn that wheels are stamped with a maximum load and inflation, and neither should be exceeded, so the wheel rating can cap the pressure even when the tire could take more.
Travel Trailer and RV Tire Pressure Chart
RV and travel trailers carry the heaviest and most valuable loads, so pressure discipline pays off here.
30-Foot Travel Trailer Tire Pressure
A 30-foot travel trailer varies widely by floor plan, so the placard on the front left side of the trailer is the starting point. It lists gross vehicle weight rating (GVWR), axle ratings, factory tire size, and recommended cold pressure. As an example, a trailer with an 8,400 lb GVWR spreads about 2,100 lb across each of four tires on average. An ST225/75R15 Load Range E carries 2,830 lb, and an ST235/80R16 Load Range E carries 3,420 lb, so both leave headroom when inflated correctly.
Weighing Matters
Average weight hides the truth. One heavy side can push a single tire past its limit, and weighing each wheel position at a truck scale shows where the real load sits.
Horse Trailer Tire Pressure Chart
Horse trailers add a live load that moves. Two horses at roughly 1,000 to 1,200 lb each, plus tack, hay, and water, can add well over 2,500 lb. An ST235/85R16 Load Range E carries 3,640 lb at 80 psi. Because animal safety is involved, many owners choose Load Range G tires and inspect tire age more often than the calendar minimum.
Carlisle and Goodyear Endurance Trailer Tire Pressure
Carlisle Trailer Tire Pressure Chart
Carlisle’s guidance is straightforward: keep pressure at the sidewall maximum, checked cold. Its Radial Trail HD in Load Range D, for example, lists a 65 psi maximum. Radial Trail tires are radial and the Sport Trail line is bias-ply, so the tire family decides which numbers apply.
Goodyear Endurance Trailer Tire Pressure Chart
Goodyear is one of the few brands that publishes load-based inflation tables for its trailer tires, and pressure can scale with the load carried. The Endurance in ST225/75R15 Load Range E, for instance, has an 80 psi maximum. Because exact numbers vary by size and by table edition, owners should pull the current table from Goodyear’s RV tire pages. More on the brand is available in the Goodyear tires overview.
Goodyear’s ST tire guidance also covers speed. Standard ST tires are rated for 65 mph, and Goodyear advises adding 10 psi of cold pressure for speeds between 66 and 75 mph. That increase adds no load capacity and must never exceed the wheel’s limit.
How to Check and Set Trailer Tire Pressure
A consistent routine matters more than any single chart. The steps below take about ten minutes.
- Find the numbers. Read the sidewall maximum, the trailer placard, and the wheel stamp. The lowest limit among the wheel and tire sets the ceiling.
- Start cold. Cold means parked for at least three hours or towed less than a mile. Shade helps.
- Use a gauge that reads high enough. A gauge that maxes out near 60 psi cannot verify an 80 psi tire. A dial or digital gauge that reads comfortably beyond 100 psi is better.
- Check every tire, including the spare. Valve extenders make inner dual tires easier to reach.
- Add air as needed. A 12-volt inflator must be able to reach the target, so its maximum rating matters. The portable tire inflator guide covers options for higher-pressure tires.
- Seal and record. Replace valve caps, and jot down the readings and the date so slow leaks become obvious.
High-pressure tires store a lot of energy. Toyo advises inflating in a safety cage with a clip-on air hose and standing well back. Never bleed air from a hot tire to reach the cold number. Wait until it cools and check again.
How Temperature Changes Trailer Tire Pressure
The old rule of thumb says pressure moves about 1 psi for every 10°F change. That figure fits a 30 psi passenger tire. Simple gas-law math shows that the change scales with pressure, so an 80 psi trailer tire moves closer to 1.5 to 2 psi per 10°F.
For example, a tire set to 80 psi in a 90°F garage can drop roughly 10 psi on a 30°F morning. That is enough to turn a correct tire into a 12 percent underinflated one before the trailer even leaves the driveway.
Hot Pressure Is Normal
Pressure rises while towing, and a jump of 10 to 15 percent over the cold reading is common on a warm day. That rise is expected and should not be bled off. The cold number is the target.
Trailer TPMS Alerts
A pickup’s dashboard warning normally does not read trailer tires. Owners who want live data add a trailer TPMS with sensors on each valve stem. Common practice among RV owners is a low alert about 10 percent under the cold pressure and a high alert 20 to 25 percent over it. A dashboard light that stays lit on the tow vehicle is a separate issue, covered in the low tire pressure light guide.
Underinflation vs. Overinflation
Both extremes shorten tire life, but they fail in different ways.
| Condition | What happens | Warning signs |
|---|---|---|
| Underinflated | Sidewalls flex too much, heat builds, and load capacity drops. | Squat look, wear on both shoulders, tires very hot after a short tow |
| Correct (cold, at target) | Firm sidewall, full contact patch, steadier tracking. | Even wear across the tread, stable trailer |
| Overinflated (above the sidewall max) | The contact patch shrinks, braking traction falls, and puncture risk rises. | Center-tread wear, bouncy ride, bulging tread |
Running an ST tire at its printed maximum is not overinflation. Overinflation means going past that number.
Beyond PSI: Speed, Age, Tread, and Alignment
Perfect pressure cannot rescue a worn-out or overspeed tire. Four other checks belong on the same routine.
- Speed rating: Standard ST tires are rated for 65 mph. Owners can decode other symbols with the tire speed rating chart.
- Age: Many manufacturers advise replacing trailer tires after five to seven years, even with plenty of tread. The tire lifespan guide explains why age hurts rubber.
- Tread depth: A tire tread depth gauge gives an exact reading, and the penny test works as a quick check.
- Sidewall cracks: Fine cracking signals aging rubber. The tire dry rot guide shows what to look for.
- Alignment: Uneven wear on one edge often points to axle problems. See tire balancing vs. alignment for the difference.
Slow leaks deserve attention too. The tire plug vs. patch comparison and the flat tire repair cost guide help decide between repair and replacement. Trailer tires should be inspected by a tire dealer before any repair is trusted.
Common Trailer Tire Pressure Mistakes
- Copying the tow vehicle’s sticker. The door-jamb label covers the pickup only. Tow vehicles that haul heavy trailers often use stronger tires, and the 10-ply truck tires guide covers that side.
- Checking hot. A reading taken right after towing is inflated by heat and looks fine while the tire is actually low.
- Forgetting the spare. A spare that has sat for two years is often the flattest tire on the trailer.
- Mixing load ranges on one axle. Mismatched tires share weight unevenly and wear out faster.
- Buying used trailer tires blindly. Age and hidden damage matter more than tread. If buying used, check the DOT date code first, and see the used tires near me guide for what to inspect.
Getting Help With Trailer Tires
Some jobs are better left to a shop, including mounting, high-pressure seating, and inspecting a suspect tire. Owners can compare options at Discount Tire Direct, Les Schwab Tire Center, and Firestone Complete Auto Care. The tire installation cost guide shows what mounting adds, and the Simple Tire coupon guide and Pep Boys tire deals guide point to savings. A stubborn bead may call for a tire bead seater.
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Trailer Tire Pressure FAQ
What should trailer tire pressure be?
For most ST trailer tires, the target is the maximum cold PSI on the sidewall, provided it does not exceed the wheel rating or trailer placard. That is typically 50 psi for Load Range C, 65 psi for D, and 80 psi for E.
Should trailer tires be inflated to max PSI?
Usually yes. Carlisle and many trailer-parts specialists advise maintaining the maximum sidewall pressure when cold. A few brands, such as Goodyear, publish load-based tables that allow lower pressures, but only after weighing the trailer and adding a safety margin.
What PSI should boat trailer tires be?
It depends on the tire. Load Range C boat trailer tires such as the ST175/80R13 or ST205/75R15 run at 50 psi, Load Range D tires at 65 psi, and 4.80-12 Load Range B bias tires at 60 psi. The sidewall is the deciding number.
How often should trailer tire pressure be checked?
Before every trip, and at least monthly during storage. Tires lose pressure slowly, and temperature swings can shift an 80 psi tire by about 2 psi for every 10°F.
Is it normal for trailer tire pressure to rise while towing?
Yes. A rise of 10 to 15 percent over the cold reading is common on a warm day. That heat-related increase should not be bled off. Pressure is always set and compared when tires are cold.
Conclusion: Use the Trailer Tire Pressure Chart, Then Trust the Sidewall
The trailer tire pressure chart comes down to a few habits. Load range sets the maximum: 35, 50, 65, 80, 95, or 110 psi from B to G. Cold pressure, checked before towing, is the number that counts. For most ST tires the sidewall maximum is the safest default, while load-based charts are a tool for owners who have weighed each axle and kept a margin.
Boat, utility, travel, and horse trailers each add their own wrinkles, from saltwater and overloading to heavy 30-foot rigs and shifting live loads. Checking pressure before every trip, watching tire age, and keeping the spare ready prevents the failures that ruin trips. When in doubt, a qualified tire dealer can confirm the right pressure.
This guide is for general education. Always follow the pressure and load limits marked on the tire sidewall, the trailer placard, and the wheel.