Estimate trailer tire pressure from the loaded trailer weight and the max load and pressure on the tire sidewall, or the load a cold pressure supports.

Linear estimate from the tire sidewall rating. The trailer placard or the tire maker’s load-inflation table takes priority.

Loaded trailer weight carried by its axles, not the tongue weight on the hitch. A scale weight is best.

The single-tire max load printed on the sidewall, e.g. “Max load 1820 lbs at 50 psi cold”.

The pressure printed with the max load on the sidewall.

Margin and pressure limit
Typical 10% allowance for uneven load sharing between tires. Enter 0 for none.

Blank uses the tire’s max cold pressure as the limit.

Related Calculators

Trailer Tire Pressure Formula

Trailer tire pressure should be set using the trailer placard and the tire manufacturer’s load–inflation table for your exact tire size and load range. If you need a rough estimate, you can approximate the minimum cold inflation pressure from the tire’s rated max load and max cold pressure:

Pₑₛₜ ≈ (Wₐₓₗₑₛ × Pₘₐₓ) / (T × Lₘₐₓ)
  • Where Pest is an estimated minimum cold inflation pressure (often in PSI)
  • Waxles is the loaded weight carried on the trailer axles (the weight on the tires; not including tongue weight carried by the tow vehicle)
  • T is the number of tires carrying that load
  • Lmax is the tire’s max load per tire at Pmax (from the tire sidewall or load table)
  • Pmax is the tire’s max cold inflation pressure (from the tire sidewall)

Important: The relationship between load and pressure is not perfectly linear for real tires, and axle-to-axle load sharing is not always equal. Treat the equation above as an estimate only. When in doubt, use the pressure on the trailer placard and the tire manufacturer’s load–inflation table, and never exceed the tire’s max cold pressure.

What is a Trailer Tire Pressure?

Definition:

Trailer tire pressure is the cold inflation pressure specified for a trailer’s tires (typically in pounds per square inch, PSI). Correct pressure helps the tire carry its intended load, manage heat, reduce uneven wear, and maintain stable handling while towing.

How to Calculate Trailer Tire Pressure?

Example Problem:

The following example outlines the steps and information needed to estimate a minimum cold trailer tire pressure (always verify against the placard and load/inflation tables for your tire).

First, determine the loaded axle weight (the weight actually carried on the trailer tires). In this example, the axle weight is 7,000 lb.

Next, identify the number of tires carrying that load. Our trailer has 4 tires.

Then, find the tire’s rated max load and max cold pressure (from the sidewall or the manufacturer’s load table). In this example, each tire is rated for 1,820 lb at 50 PSI.

Finally, estimate the minimum cold pressure using the approximation above (in the calculator, set the safety margin to 0% to match):

Pest ≈ (Waxles × Pmax) / (T × Lmax)

Pest ≈ (7000 lb × 50 PSI) / (4 × 1820 lb)

Pest ≈ 48.08 PSI

Because this estimate is close to the tire’s maximum cold pressure, you would typically be near the tire’s rated limit for that load. If your calculated value exceeds the tire’s max cold pressure (or your per-tire load exceeds the tire’s max load), the correct fix is to reduce load or use higher-rated tires—not to exceed the tire’s rated pressure.

FAQ

What happens if my trailer tires are underinflated?

Underinflation can cause excessive heat buildup, increased tire wear, and potentially unsafe towing conditions. Underinflated tires flex more, which increases heat and can raise the risk of tread separation or blowouts—especially on trailers.

How does terrain affect recommended tire pressure?

For most on-road trailer use, follow the trailer placard and the tire manufacturer’s guidance (often near the tire’s rated cold pressure for the load). Lowering trailer tire pressure for “traction” is generally not recommended unless the tire/trailer manufacturer specifically permits it and you are operating at appropriate low speeds, because low pressure can increase heat and damage risk.

Should I adjust tire pressure for changing loads or weather?

Yes. Tire pressure should match the load being carried (per the placard or load/inflation tables). Also check pressure when tires are cold—pressure changes with temperature (a common rule of thumb is about 1 PSI per 10°F or ~0.07 bar per 10°C). Seasonal temperature changes can require re-checking and adjusting cold pressure.