Anyone in the Chicago area with Audi 19” 5 spoke ‘rotor’ wheels willing to do a wheel swap test with me for a few days?

I’ve been fight a steering wheel vibration problem since I bought my 2015 Audi TTS in April 2016 and I’m at the end of my rope.

Here’s the detailed summary:
1) Car had 2000 miles, came with 255 35 R19 snow tires mounted on 19” 15 spoke Audi wheels.
2) I bought Hartmann 5 spoke “rotor” wheels. They make replica wheels for German cars. Also bought Dunlop 255 35 R19 summer tires.
3) From the beginning, using the Hartmann / Dunlop setup gave me steering wheel vibration – but only occasionally, especially at 82 mph +/- 3 mph, and especially when moderately accelerating through that speed. When driving on long trips at high speed, the vibration comes and goes every few minutes.
4) Trying to eliminate this, I had the wheels rebalanced 5 or 6 times over 2 years by 4 different places. (Starting to lose count) Of course they all did road force balance.
5) After the first year (2016) I bought a new set of tires (Michelin Pilot Super Sport) to see if the problem would go away. The vibration is less, but the main characteristic is still the same.
6) I’ve tried different tire pressures, different tire & wheel positions to no effect. The only thing that may have reduced the vibration is cooler weather (50F.)
7) This is a very aggravating problem. Its most annoying when taking the car on vacation trips when driving at high speeds all day. Kind of ruins the trip.
8) During the winter months, I’ve put the Audi OEM wheels with Bridgestone Blizzak tires back on, and never notice any vibration. Hmm….
9) So given all the wheel balancing, and having tried two different sets of brand new summer tires, the only common denominator left is the Hartmann wheels. I’m tired of throwing money a problem I have totally failed to resolve. One difference between Audi wheels and Hartman is the offset. The Hartmann wheels have +47 Offset, the Audi +52. 5 mm difference. Can’t use spacers, the Hartmann’s would need to go into the rotor area more to be equivalent. So I’m curious if the wheel spacing being a bit different can affect the “scrub radius” enough to cause a difference in the torque moment on the tire patch on the ground.
10) I want to try 19” Audi OEM 5 spoke rotor wheels (love the look) to see if my problems would finally go away. Anyone in the Chicago area willing to do this test with me and swap wheels for a few days? If this is the cure I’ll fork over the coin for actual Audi wheels, about double the price of Hartmann. I can’t keep throwing money at this problem without some hope that I’m going down the right path.

Thanks!