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Tire pressure guide

# Tire pressure guide

## What is the correct tire pressure?

The correct tire pressure is printed on a label inside the driver's door jamb (or sometimes the fuel filler cap) — not on the tire sidewall. That sidewall figure is the maximum cold inflation pressure, not the recommended operating pressure. Most passenger cars run 30–36 PSI (2.1–2.5 bar / 207–248 kPa) cold. Always check when the tires are cold (driven < 3 km).

## Where to find the recommended pressure

- **Door jamb sticker** - inside the driver's door frame, on the B-pillar, or inside the door itself. This is the authoritative source.
- **Owner's manual** - lists pressure for all load conditions: driver only, full load, and trailer towing.
- **Fuel filler cap** - some models, especially older European cars, print the pressure here.
- **NOT the tire sidewall** - the number marked there, for example "MAX 51 PSI / 3.5 bar", is the maximum cold inflation pressure the tire casing can safely hold. It is not the manufacturer recommended operating pressure for your car.

## Pressure units conversion

| Unit | Full name | Typical car range | Notes |
| --- | --- | --- | --- |
| **PSI** | Pounds per square inch | 30-36 PSI | Standard in USA, UK |
| **bar** | Bar | 2.1-2.5 bar | Standard in Europe |
| **kPa** | Kilopascal | 207-248 kPa | 1 bar = 100 kPa |

Quick conversion: **1 bar = 14.504 PSI = 100 kPa** . So 2.3 bar = 33.4 PSI = 230 kPa.

## Effects of incorrect pressure

| Condition | Tread wear | Fuel economy | Handling | Risk |
| --- | --- | --- | --- | --- |
| **Correct pressure** | Even across full width | Optimal | Normal | None |
| **Under-inflated (low)** | Excessive wear on outer shoulders | Up to 3% worse per 10 PSI low | Sluggish steering; risk of aquaplaning | Overheating, sidewall failure, blowout |
| **Over-inflated (high)** | Excessive wear in centre tread | Slightly better rolling resistance | Harsh ride; reduced grip | Increased susceptibility to impact damage |

## Temperature and pressure: the 1 PSI rule

Tire pressure changes approximately 1 PSI (0.07 bar) for every 10 °C change in ambient temperature. This is why tires that were correctly inflated in summer may trigger the TPMS warning in winter.

| Temperature change | Pressure change |
| --- | --- |
| +10 °C | +~1 PSI (+~0.07 bar) |
| -10 °C | -~1 PSI (-~0.07 bar) |
| Summer -> winter (-20 °C) | -~3 PSI (-~0.2 bar) |

Always re-check and adjust pressure at the start of each season and after any significant temperature swing of 10 °C or more.

## TPMS - Tire Pressure Monitoring System

TPMS is mandatory on all new cars sold in the EU since 2014 and USA since 2008. The warning light, a cross-section of a tire with an exclamation mark, illuminates when any tire is 25% or more below the recommended cold pressure.

- **Direct TPMS** - a pressure sensor inside each wheel transmits real-time readings. Requires valve-cap battery replacement every 5-10 years.
- **Indirect TPMS** - uses ABS wheel-speed sensors to detect when an under-inflated tire rotates faster than the others. Cheaper but less accurate; must be reset after inflation or rotation.
- **TPMS only warns at 25% low** - a tire can be 10-15% low, several PSI, without triggering the light. Monthly manual checks with a gauge are still necessary.

## How to check and inflate correctly

- Check when tires are cold: parked for at least 3 hours or driven less than 3 km.
- Remove the valve cap and press a calibrated tire gauge firmly onto the valve stem.
- Compare the reading to the door jamb sticker. Add air if low; release air by pressing the valve pin if high.
- Re-check after inflating; air compressors often add slightly too much.
- Replace the valve cap. Repeat for all four tires and the spare.

## More tools

- [Tire rotation guide](https://tirefitlab.com/learn/tire-rotation/)
- [Tire tread depth guide](https://tirefitlab.com/learn/tread-depth/)
- [Tire age guide](https://tirefitlab.com/learn/tire-age/)
- [Speedometer error guide](https://tirefitlab.com/learn/speedometer-error/)
- [Tire size calculator](https://tirefitlab.com/tire-size-calculator/)
- [Tire & wheel reference guides](https://tirefitlab.com/learn/)

[Last reviewed: 2026-06-21](https://tirefitlab.com/methodology/)

Seasonal check

## Planning a long summer drive?

Use the budget and running-cost tools before a trip, especially if the current tires are worn or the replacement size changes diameter.

[Estimate tire budget](https://tirefitlab.com/tire-budget-calculator/)

## More in this topic: Ownership and maintenance

Pressure, age, wear, cost and service decisions after the tires are fitted.

- [**Tire age & DOT date code guide** How to find and decode the DOT date code on your tire sidewall to determine its manufacturing week and year, and when to replace old tires.](https://tirefitlab.com/learn/tire-age/)
- [**Cold tire pressure guide** How cold tire pressure works: the 1 PSI per 10°F (0.1 bar per 8°C) temperature rule, when to check pressure (cold only), morning vs driven-tyre readings, altitude effects, and seasonal adjustment.](https://tirefitlab.com/learn/cold-tyre-pressure/)
- [**Tire pressure for heavy loads and towing** When and how to increase tire pressure for heavy loads: XL (Extra Load) tire pressure requirements, laden vs unladen recommended pressure, adjusting rear axle pressure when towing, front vs rear axle pressure differences, and what happens when you tow on under-inflated tires.](https://tirefitlab.com/learn/tyre-pressure-load/)
- [**Trailer and caravan tire pressure guide** Correct tire pressure for trailers, caravans, and horse boxes: why trailer tires are inflated much higher than car tires, how to find the right spec, load-dependent pressures, and the consequences of under-inflation on a towed vehicle.](https://tirefitlab.com/learn/trailer-tyre-pressure/)