Sat in it now, first turn on infotainment system. Then press 'car' button - 3rd down on rhs- then press 'setup' - middle of screen, at the bottom, then select 'tyres' -2nd down- then 'calibrate' , finally 'confirm'.
Not complicated at all. No. No need for such a basic thing as a 'button' .
Please note we have the 'upgraded' sound system with nav, so yours might be different, perhaps less (or more!) levels. Who needs a PS when you can 'play' this all day......