Also depends on the gauge. I've seen up to a 3 psi difference between gauges (decent gauges too...).

Experimenting like you did is the only way to find the "sweet spot" for your vehicle.

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Kirk
Las Vegas
2016 X5 40e Mineral White/Black Dakota Leather, ZLL, ZCW, ZDA, ZDB, ZPP, multi contour seats, rear side window shades, HK stereo
2011 E90M3, 6-speed manual