Peter,
Is this front or rear or both? If you got new wheel nuts are you sure they are 12mm x1.5? It may pay just to get a thread gauge to check or die to run over the studs.
There's a slim possibility your front studs could be imperial, some folks were using front Mustang rotors as replacements and the 12mm studs are not a tight fit, as the rotors were designed for a 1/2-20 stud. It could be that the previous owner fitted the imperial studs to match.
Julian
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