Its not just the ET, also the combination of diameter, width that affecrs clearance and then the thickness of the wheel centre (or knave, if you will) and if thatvworks with the oem stud length.
Some fit, some don't.
Original alloys required a slightly longer stud of around 45mm iirc so most use 50mm and the closed end wheel nuts still fit without popping their caps off.
1985 Oettinger 3.2 Caravelle RHD syncro twin slider. SA Microbus bumpers, duplex winch system, ARC 7X15 period alloys