At my wits end: tire/wheel problem or something else?

Guys I am in need of some help. I bought an 06 325i (e90) sports package as a CPO car in 2009. Ever since I have had it, it has had a speed related droning/howling noise and vibration through 3 sets of tires. For the first two sets the front tires eventually developed a feathered wear pattern on the inside edges. The rears seem to wear fine.

The most recent tire purchase is a set of Bridgestone s04 pole position non-RFT summer tires. They were road force balance down to single digits and the car (again) was aligned when I put the new tires on. (See attached). I had the thrust arm bushings and front sway bar bushings replaced within the last year.

The most recent set of tires have been on the car for ~3000 miles and while I can't see any uneven wear, I am getting a lot of noise and I have the same vibration in the same speed range. The noise starts around 45mph and the vibration is more of a rhythmic "rumble" that comes on at about 70mph and is very pronounced by 80mph.

The car been inspected 3 times and everyone says it "looks tight". But clearly something is wrong. What gives? Are the factory alignment specs to blame for this? Are the road force numbers OK, or do they need to be lower to rule out vibration? Should I be looking somewhere not wheels/tires? I have never had issues like this with any other car I have owned. Help?

Alignment:

Toe

Front: 7 minutes per side (range 7min +-2min)

Rear: 9 minutes per side (range 9min +-2min).

Camber

Front: -32 minutes left side, -22 minutes right side (range -18min +-30min)

Rear: -1 deg 30 minutes on both sides (range -1deg30min +-5min).

Roadforce numbers:

RF 10lbs
LF 2lbs
RR 2lbs
LR 5lbs