i dont know if was mentioned before, but i always see the turbo gauge in bar and tyre calibration is always in psi... lfs both is psi or bar(turbo and tyres). how about make an option to select if tyre is psi or not so as the turbo??

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Slovenia here, tyre pressures always in bar.

That isn't true. It really depends on where you live. Where I am, psi is as widespread as bar and kPA, although for automotive tire use, psi offers the most convenient numbers.

In the UK tyres are nearly always done in psi.

Technical turbo talk is done in pressure ratios anyway, not psi or bar, it's only the man on the street that can't cope with 'ratios' that uses relative pressure (although they probably wouldn't know it was relative even if you spent three years informing them of the different pressure datums).

Well, bars happens to be units correlated with a standard atmospheric pressure(barometric atmospheres). However, from a technical point of view, pressure ratios offer the best method for comparsion.