I had a set of OEM Style 73 wheels on my E46 330i with 205 50 17 Conti extremecontact DW on them. No issues with vibration or handling, but was just time for new tires. I found a set of OEM style 193s. They were in pretty good shape with no major signs of damage except one of the front wheels has some curb rash. The rears had 255 35 18 Michelin Pilot Sports on them and the fronts had a mismatch set of 225 40 18, all looked in great shape with plenty of tread depth. I got them and put them on the car, took a short test drive (not over ~45mph) and no issues. Later toward the evening I left to go somewhere and got up to 60+mph. At this point I started to get pretty bad vibration through the car. It was determined to be the rear since there was no shake in the steering wheel. I figured they were just really out of balance. The Prev Owner still had the matching fronts for the Michelin Pilot Sports, so I went and picked them up. If I had to balance them, I might as well swap the matching tires on the front. Took them to a Mom and Pop shop, since how hard is it to mount and balance some tires. Had the fronts mounted and balance and rears balanced. Left the shop and the vibration was still there. Went home and swapped the rear wheel I thought was the "bad rear 193" with my old Style 73 (overall diameter stock was within 1mm). The vibration went away. Swapped the "good rear 193" into the same spot and put the Style 73 in it's place, no vibration. I wanted to try another of the 193s in the same spot as the "bad one" to make sure it wasn't anything suspension related in that one corner.

So I figured maybe this Mom and Pop wheel place just did a crappy job. Took it to Discount Tire, had them balance the "bad 193". They said there was way too much weight on the inside of the wheel. Vibration still there. Took back yesterday and had them do all 4 wheels to eliminate any other wheels being the problem. They then said that one of the fronts was .5 oz off and the rear was 2 oz off. Vibration still there. Swapped the old Style 73 where the "bad 193" was and again, no vibration. Took back to them today, they Road Force balanced it, added 1 oz to the inside, and Road Force checked it again to make sure it showed in balance. Took out, up to 60 mph and vibration still there!

They stated the tire has no separation and that it is in good shape. Tread depth left is about half of the new tire, so that's not the issue, with no uneven wear or odd spots showing up.

I'm not sure what else left to do. Take to a wheel repair shop and have them examine it? Could the tire be the issue with no visible signs of issues? Could the mounting surface on the wheel to the hub be causing a problem?

Any suggestions welcome, thanks!