Meters, liters, and even Celsius are fine. But Pascals are the hyperinflation of pressure units. 5 psi? That'll be eleventy million pascals. Maybe if I had a bike pump that had 50kPa increments alongside Psi, I could gradually figure it out.
And conveniently, the atmospheric pressure is very close to 100kPa. So you can use a derived unit called a "bar" which is 100kPa.
Your bike tires need to be at around 3 bar.
Yo, what? I'm pretty sure I do my bike tyres up to about 6.5 bar. And that's down from the 7 I used to use until I heard that lower pressure creates lower rolling resistance and is better.
Ah, I see. You likely have a road bike, I have a mountain bike.
- higher rolling resistance (energy to flex the tyre)
- softer ride (but don't go so low that stones or potholes pinch the rim)
- better grip (surface area in contact with the ground)
So go max pressure on a smooth dry road, but go softer in the wet, or on a rough road/mountain.
Similarly, the tread on the typre will also affect energy absorption. Go for smooth road bike tyres, or slick MTB tyres, on a smooth road, but obviously super gnarly for rough mountain trails.
In precision machining, you'll also hear "tenths" (one tenth of a thou or 0.0001").