I have a friend that has a late '70's Porsche 911 Turbo. He had a vibration issue at speed that he could never solve. The culprit turned out to be his steel McGuard locking lug nuts. They were so much heavier than the OEM Porsche aluminum nuts, it created a huge imbalance that all the shops he took it to, missed. The large Porsche bolt circle (130mm) didn't help. This is why Porsche sells their own locking lug nuts and bolts. Theirs weigh the same as the OEM nuts/bolts.
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