The PSI-to-bar conversion factor
One pound-force per square inch equals approximately 0.06894757293 bar. Multiply PSI by that factor to calculate bar.
For the reverse direction, one bar equals approximately 14.50377377 PSI. Bar is defined as exactly 100,000 pascals.
Tire-pressure examples
A tire pressure of 32 PSI is approximately 2.2063 bar, usually shown as 2.2 bar. A pressure of 35 PSI is approximately 2.4132 bar.
Follow the vehicle manufacturer's cold-tire recommendation rather than the maximum pressure printed on the tire sidewall.
Gauge pressure and absolute pressure
Many tire gauges report pressure relative to atmospheric pressure, called gauge pressure. Absolute pressure includes atmospheric pressure and uses a different zero point.
A unit conversion does not change the pressure reference. Confirm whether a specification uses PSIG, PSIA, barg, or bara.
Rounding pressure safely
Everyday tire readings may be rounded to gauge precision, while engineering and calibration work may require more digits and documented uncertainty.
Do not add precision absent from the source measurement. A 35 PSI reading does not become more accurate because the converted result shows many decimals.