Now isn't that amazing, my experience is that they are a little nosier than i would like, but no more so that other low profile tyres i had on other cars, i found they balanced up well with minimal lead, i also felt they were great on dry roads but progressively let go in the wet, personally i would prefer a little more grip in the wet, but then mine have worn extremely well, so i guess you cant have long life and sticky tyres in the same package.

i would say that if you cant balance them and as you stated you have tried them on another car withthe same results i would personally remove the tyres from the rims and see if you have a bent or badly out of balance rim, if the rims are ok i would return the tyres NOW as i wouldnt put up with out of balance wheels ( or warped brake rotors )

i dont see the logic in putting up with something thats not working for you.

maybe as stated the manufacturing tolerance are not as close as they should be, or maybe they are and you have a damaged / bent rim???

what ever, you need to investigate further.