Right tire pressure

Hi,

I have 348 wheels with original size Pirelli tires for a 348 mounted on my Mondial. I was looking at the 348 owners manual to see what is the right tire pressure and the pressur is given in mm of mercury or in BAR. Both mesure when converted to PSI are different

mm Hg gives 37.9 psi front and 39.4 psi back
in bar gives 34.8 psi front and 37.7 psi back

Which is any is right?

Just wondering.
Patrick