Help! rear tire rub with 255/40/17 on 93 740i (archive)

After almost 2 months, I finally received my set of chrome RH X-rad tires from an internet company (worst experience, should have stuck with tirerack..but that's another story). These are the wheels which look like the AC Schnitzer; and they are a fairly good replica (supposedly TUV approved, German made, etc). They are hubcentric (no special mods required)

I have a 1993 740i and I purchased 235/45-17 (17x8) on the front and 255/40-17 (17x10) on the rear. (Michelin Pilot Sport)

I have 2 problems:
The first is that the rear wheels rub when I have 2 or more passengers in the rear. I spoke to many individuals before the purchase and they all stated that 255/40-17 will fit fine. I have even seen 265/40-17 on certain E32's. What gives? What do I need to do? I have the self-leveling suspension in the rear...could it be bad? Would a sway bar help? Should I replace the suspension set-up altogehter and go with regular springs and shocks?

The second problem deals with minor vibration occurring at about 50mph. When I received the wheels, the company forgot to ship the accessories (lugs, centerpieces, etc...I am still waiting for these) I installed the wheels using the old steel stock lugs. I immediately noticed vibration between 40-55mph. After re-balancing the wheels and still experiencing the vibration, several individuals stated that it was probably the lugs. I replaced the lugs with aluminum lugs at a local wheel place (though NOT the lugs which were supposed to come with the wheels...they have not come yet). Although most of the vibration disappeared, there is still some minor vibration at almost exactly 50mph. I don't feel the vibration either below 48mpg or above 52 mph. Could it still be the lugs? What causes the vibration using the stock lugs? Are there special lugs which are supposed to go with these RH wheels? Any other suggestions as to the possible causes of the vibration?

Any help will be greatly appreciated.

Thanks.

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