You can also calculate it with spreadsheet , in wich I use the same system , that is used to make these lists. Once got hold of it and worked it out.
How do they come to the 42 psi? I suppose this list is for XL , Extra load, reinforced tires that work with a reference pressure of 2,9 bar wich is 42 psi ( I estimate). This is for up to 220km/h , for higher speeds there is a system for highgening up this reference pressure.
http://cid-a526e0eee092e6dc.office.l...0tyre-pressure
In this map the spreadsheets and examples for re-calculating the advice pressures for non oem tires , but also to check the original and see if you can go lower for sertain conditions.
Download and open the spreadsheets in Excell or likewise programm to work with it, the browser will try to open it but cant handle the protection and data-validation I used in it. If this message appears, click on the name of the spreadsheet at the line above to go to a page where you can download it.
I checked the list and it calculates with the right save European calculation for normal car tires. But if you fill in the advices of the car , they are made for up to maximum speed of the car with the original speedcode of the tires.
This could make the conversion to other tires like you do insecure.