Tearing my hair out but I can't for the life of me find anything to have the tyre pressures in Assetto Corsa or Competizione read out in PSI instead of BAR without changing everything over to imperial.
Even just having BAR to two significant figures would be better.
Absolute nightmare especially for competizione because the optimum tyre pressures of 27.3 - 27.8 equates to 1.9 -1.9 BAR, there's just not enough granularity with BAR to one significant figure to make the tyre pressures given by crew chief of any use.
Edit: I'm aware of the setting for iRacing, don't think that it carries over for ACC.
Also the help documentation supports tyre pressures for pitstops but I've never had much luck when giving the pressures in psi, seems to start ignoring me or just hears something different.