Had to get an adaptor made to put air in my my Merc tyres
Never trust em though and always use a digital gauge to check afterwards.
My VRF used to let me know when the tyres were down, drop 1-2PSI in the
front and it wobbled like my gut ... Drop 1-2 in the back and it tram-lined
all the way to the garage, always found the SV stable on low(ish) tyres
though ...