From what I've been told - it has nothing to do with the tires nor the psi. It is the actual "racks" that need to be replaced as mentioned by jimmy3526 and what the GM at my dealership personally told me. SO - whatever your dealership service department is doing other than replacing the front "rack," it will only attempt to mask the problem. They tried several things with my car - it improved slightly but the vibration was still there. If they can mask it for you now, it might come back, especially if they are messing with the psi. Take my advice, tell them you've heard that BMW is shipping front "racks" to fix this problem and you insist they find out about IT. You don't spend this kind of money to have them screw around with your car without fixing it once and for all.
12/13/12 2013 528i Alpine White, Oyster/Black Dakota Leather, Prem Pkg, Tech Pkg, Premium Hi-Fi Sound, Heated front Multi-Contour seats
Just Ordered 2/27/13: 2013 328 Conv, Liquid Blue Metallic, Oyster/Black Dakota Leather, Conv Pkg, Premium Pkg, Prem Sound Pkg, Navigation Sys
To Replace our leased 2010 128 Conv, Sports Pkg
Previous BMW: 2013 328 "Trade Assist"
Previous BMW: 2009 328 Convertible
Previous BMW: 2008 535i
Previous BMW: 2007 550i