Being backward, these guys still use the old Imperial system & refer to PSi tyre pressures.
That's Pounds per square Inch (we stopped using Pounds & Inches in the early 1960's #progressive).
We use Bar or KPa (basically the same thing)
The other thing I noticed is that they barely deflate.
Guys refer to dropping (dropping!

Now 35, 20 & 15 PSi are not that soft:
35 psi = 2.41 bar or 241 KPa
30 psi = 2.07 bar or 207 KPa
25 psi = 1.72 bar or 172 KPa
20 psi = 1.38 bar or 138 KPa
15 psi = 1.03 bar or 103 KPa
So these guys are 'airing down' or 'Deflating' to around 1.8bar & sometimes to around 1.4 bar.
They NEVER go below 1.0 bar.
If I deflate, then I either go to 1,2, or 1.0, if its thick sand, I'll drop lower, I've been to 0.6 bar.
I can't 'Deflate' to 30psi because that's basically my normal running pressure...
Anyone agree with these Canucks, Yanks & Ozzies?