Well maybe exaggerating a bit But after googling on and off for a couple of days, and deciding 10mm all round (on my 19x8j ET49’s) would be doable (I’m going to use the Racingline stud conversion, and that maxes out at 10mm) I started looking at spacers. Decided H&R hub entries are the way to go - but wait; why are there so many sets of the same thickness suitable for my car on offer? Ah, now I find out that there are versions with 4x45 and 6x45 degree chamfers, and for different maximum hub heights! So I think my wheels (both winter and summer) are 6x45, so that’s good. Can’t see for the life of me what difference a 12mm and 15mm hub height would make. ETA - I guess it’s so the existing hub doesn’t stick out the other side of the spacer.