Tire pressure sweet spot

[StanF18]

I know the X5 tire pressure topic has been discussed many times, and I am not looking to start any heated arguments.
Justed wanted to share my personal experience after playing around with different inflation pressures. Quite a while back, I had found the "recommended" 33 psi cold to be inadequate (subjectively), both in terms of handling and in terms of too much rolling resistance. So I've always run at higher settings, but it was a bit difficult to determine what was "optimal". Luckily, the tactile steering feedback you get from a BMW is so excellent (compared to say a Toyota), that you get a pretty good feel for when the vehicle is gripping well on a hairpin turn, versus sub-optimal gripping, versus very poor gripping.

What I have found is that the old adage holds true: if a little bit of something is good, it does NOT mean that more is even better. Just for the hell of it, I experimented as high as 38psi front/40psi rear. Not a good place to be. While the rolling resistance was noticably low, the X just did not handle well on rapid lane changes or on sharp curves. There was a dramatic decrease in gripping power, and the smaller contact patches became even more obvious on wet pavement. I ran at this setting for a good 3 weeks just to convince myself, and it was obvious that handling was compromised in terms of grip and maneuverability.

I scaled back to 36psi front/37psi rear. This seems to be a "sweet spot" in terms of all-around handling. The steering feedback is fantastic and the tires grip with a lot of bite on both dry and wet pavement. The sense of "floating" and imminent loss of grip that I saw at 38/40 was gone. At the same time there was none of the sluggishness that was obvious at the textbook low 33psi.

Just for the record, I am running a 19" 255/285 staggered setup.

Just wanted to share. YMMV.