Tire presssures are set for balanced handling. If you want to raise them at all, keep the delta between factory setting and increase by X psi. 32 front, 36 rear becomes 36 front 40 rear etc when raising by 4.

This is the same reason that Corvairs and VW Beetles got into trouble...

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'04 X5 3.0 5AT with 300,000+km - Black
'08 535xi 6AT with 290,000+km - Titanium Silver