While the Max tire pressure stamped is also the PSI that allows for the maximum load capacity of the tire that has nothing to do with your average bike, let's say hypothetically that the max load index of the front tire is 860 lbs and the max load for the rear is 1201 lbs (2061 lbs total) but yet the bike has a gross max weight rating (loaded all-up) of just 992 lbs, you don't need nor would you generally want to run the tires at their MAX PSI.I've heard that information a bit differently from a Michelin tech. The pressure stamped on the side of the tire is the pressure at which the tire has it's best load carrying ability. Any more pressure than that does not increase the load it can carry.
It's hard to argue against going with what's stamped on the swing arm of your bike. However, my feeling on that is that is the pressure BMW engineers (and lawyers) want in the tire when the bike is fully loaded at it's max vehicle weight. If you buy in to that assumption, then does it not make sense that you'd get better performance and tire life from the tires running a slightly lower pressure if the bike is not fully at its max weight?
How many of us are wearing out out tires in the middles? Is that situation made better or worse by inflating the tire to the swing arm listed pressure vs. say, about 10% less?
My personal data for this rationale comes from having three different BMW bikes, an S1000RR, K1600GT, and the 1200GS LC. I've gotten great performance on all these bikes running pressures less than recommended by the manual or swing arm sticker. The 1600GT recommended 42/42. I ran that bike for tens of thousands of miles at 38/38. My S1000RR recommended 36 front/42 rear. The dunlop tech (and California Superbike school) recommends 31F/29R for the track and I ran 3 psi more for the street on each end. On my GS running TKC80 tires, I run them in the mid-20's off road and in the mid-30s on road.
I have the pro mode plug in mine and run it in Enduro Pro off-road. That mode turns off the tire warnings on the dash in the acknowledgement that riding off-road will typically have the tires aired down below their alarm thresholds.
My advice is to do whatever puts your mind at ease but don't sweat a few psi here and there.
All of us wear out tires in the middle, I find that the road tires I use (Michelin Anakee III and Pilot Road 4's) both last longer with slightly more pressure than BMW recommends.