Tyre Pressure Calculator
Convert between PSI, Bar, kPa, and kg/cm² instantly. Adjust cold tyre pressure for hot temperatures using Gay-Lussac’s law to ensure accurate readings and optimal vehicle safety.
Tyre Pressure Converter & Adjuster
Convert units and compensate for temperature changes
Leave both temperatures the same for a pure unit conversion. Enter different values to see how heat affects pressure.
Pressure Results
Converted values and temperature adjustments
Enter your tyre pressure and temperatures, then click Calculate Pressure to see the converted and adjusted values.
Standard Tyre Pressures
General recommendations for cold tyre pressures. Always check your vehicle’s door jamb sticker for exact specifications.
| Vehicle Type | Recommended (PSI) | Recommended (Bar) |
|---|---|---|
| Passenger Car (Normal Load) | 30 – 35 PSI | 2.1 – 2.4 Bar |
| Passenger Car (Fully Loaded) | 35 – 40 PSI | 2.4 – 2.8 Bar |
| SUV / 4×4 | 32 – 38 PSI | 2.2 – 2.6 Bar |
| Light Truck / Van | 35 – 45 PSI | 2.4 – 3.1 Bar |
| Motorcycle (Solo) | 28 – 32 PSI | 1.9 – 2.2 Bar |
| Motorcycle (With Passenger) | 32 – 36 PSI | 2.2 – 2.5 Bar |
Tyre Pressure FAQ
Everything you need to know about maintaining optimal tyre pressure for safety and efficiency.
The correct tyre pressure for your vehicle can usually be found on a sticker inside the driver’s door jamb, in the owner’s manual, or on the fuel filler flap. For most passenger cars, it ranges between 30 and 35 PSI (2.1 to 2.4 Bar). It is crucial to use the manufacturer’s recommendation rather than the maximum pressure printed on the tyre sidewall.
Driving heats up the tyres due to friction and flexing, which increases the air pressure inside. ‘Cold’ tyre pressure refers to the pressure when the vehicle has been parked for at least 3 hours or driven less than 2 miles. Manufacturers specify cold pressures to provide a consistent baseline. If you check them when hot, the reading will be artificially high by 3-5 PSI.
According to Gay-Lussac’s Law, the pressure of a gas in a constant volume is directly proportional to its absolute temperature. As a general rule of thumb, tyre pressure changes by about 1 PSI for every 10°F (or ~0.07 Bar for every 10°C) change in ambient temperature. This calculator uses the exact Gay-Lussac formula to give you precise adjustments.
PSI stands for ‘Pounds per Square Inch’ and is the standard unit of pressure in the imperial system, commonly used in the US and UK. Bar is a metric unit of pressure, where 1 Bar is equal to 100,000 Pascals (or 100 kPa). 1 Bar is approximately equal to 14.5 PSI. Most European vehicles use Bar, while American and British vehicles often use PSI.
You should check your tyre pressure at least once a month and before any long journeys. Tyres naturally lose about 1-2 PSI per month due to permeation (air escaping through the rubber). Checking them regularly ensures optimal fuel efficiency, tyre lifespan, and vehicle safety.
If pressure is too low, the tyre bulges, causing excessive heat buildup, poor fuel economy, sluggish handling, and premature wear on the outer edges. If pressure is too high, the tyre bulges outward in the center, reducing the contact patch with the road, leading to a harsh ride, poor traction, and premature wear in the center of the tread.
Yes, altitude affects atmospheric pressure, which in turn affects your tyre pressure gauge reading. As you drive to a higher altitude, atmospheric pressure decreases, causing your tyre pressure gauge to read slightly higher, even if the absolute pressure inside the tyre hasn’t changed. Conversely, descending to a lower altitude will make the gauge read slightly lower.
Gay-Lussac’s Law states that the pressure of a fixed mass of gas is directly proportional to its absolute temperature, provided the volume remains constant. The formula is P₁/T₁ = P₂/T₂. Because tyre volume is relatively rigid, this law perfectly describes how tyre pressure increases as the tyres heat up from driving or a warmer environment.