It really is rather simple-

Use whatever pressure gives you the ride, handling and wear you want- provided you stay under the labeled maximum. (and probably over the numbers BMW puts on the side of the door)

I have 5 cars, and a few other things with wheels, and I have no idea WHAT the manufacturer says to use for inflation!

OP- the observation that you will get excessive outer edge wear on the fronts due to the heavy front engine car plowing the tires around the turns is spot on- increase the pressure, you will get much less sideways roll. I use higher pressures in the front as compared to the rear, X5 and M5. The X5 has 37 in front 255/50-19 Mich RFTs

Again, as long as you are under the tire mfg max, you are free to experiment, IMO.