Pressure converter
Seven units of pressure at once. For tyres, the numbers to know are that 1 bar is about 14.5 psi and a typical car tyre runs around 2.2 bar or 32 psi.
How to convert pressure
One distinction is not visible in the numbers and matters a great deal: gauge pressure versus absolute. A tyre gauge reads zero in open air, so it is measuring pressure above atmospheric, that is gauge pressure, sometimes written psig. Absolute pressure counts from a vacuum and is about 14.7 psi higher at sea level. These conversions are of the number you have, whichever kind it is; converting 32 psi to 2.2 bar is correct for both, but comparing a gauge reading to an absolute one without adding atmospheric pressure is not.
Questions
About 14.504. A tyre at 2.2 bar is about 32 psi.
Gauge reads zero in open air; absolute counts from vacuum and is about 14.7 psi higher at sea level. A tyre gauge shows gauge pressure.
Exactly 101,325 pascals by definition; about 14.7 psi or 1.013 bar.
It is a survival of the mercury manometer. 120 mmHg is about 16 kPa.
Not strictly, but it is accepted for use with SI and is exactly 100,000 pascals, which is close enough to one atmosphere to be convenient.