[Mr Clean]

I don't have an answer to your question, but I will research and try to get back to you on that, but I do have a suggestion to offer. But first, story time!

I had spacers on my e39 and the car would vibrate and shake at the speeds you described. They were the ECS tuning brand with extended lugs and very well made. Keep in mind I was always taking my wheels off due to being a busybody and constantly adjusting my coilovers and doing other mechanical work. One day I was due for an alignment and one of the workers shook my wheels to make sure I didn't have any damaged suspension components (which wouldn't allow me to get the proper effects of the alignment) and he found that I needed a new tie rod. I said to him, there's no way I did it last month and we argued for a while. He decided to do the alignment anyway and took the wheel off by hand since the impact wrench was in use. To his surprise the wheel came off quite easily and as he took a closer look at the other wheels he realized I didn't seat the spacers correctly and as a result, the lugs couldn't properly tighten thus causing my vibration at speeds. What he did to seat the spacers correctly was to clean the hub, clean the center bore of the wheels, put the spacers on, and without the wheels, use the impact wrench to tighten the lugs in a star configuration. Then he would remove the lugs and put the wheels on and tighten the wheels. After that, I never experienced any shaking again. It was a s simple as that. Try that out and see if your problem is solved.