So pictures are of door label and OEM tyres fitted. The fitted tyres are not listed on the label (no 92W on the label, and 2 psi different pressures for 92V and 92Y speed ratings for the label). What pressures should be used?

https://goo.gl/photos/GtT4EyeMShN9qm9U8

https://goo.gl/photos/srJQbU7pZWnBRSX17

http://www.tyre-pressures.com/models

Have a look on this site and see if you can match up an average for the tyre specs...would probably go to the higher reading to start with and drop down if you find handling a little too light or if you believe there is accelerated wear occuring across the tyres.

Wow. That site has it as (for the only 18 rim they list) as:

225/40R18 Y 92    Front: 2.2 BAR / 32 PSI    Rear: 2.0 BAR / 29 PSI

For that tyre, Audi door label has it as 39/36 PSI! That's one hell of a difference...

Think I will split the difference between the two speed ratings on the Audi door label for that size of tyre ...

 

36 psi is correct if you've got a quattro. It's significantly higher on the quattro due to the increased weight of the transfer box (adds about 100-150 kg over the front axle if I remember rightly) :)