Well I am pleased to report Scott was right... though only just
I just couldn't resist offering up the wheels to the car after picking them up from being polished, and I was super nervous about the wheels not fitting on the rears... the front's are fine as there is so much wiggle room but the rears were tight already with the 15x7 et12 Alpina reps, so I couldn't believe the WORK wheels fitted so well!
The specs are 15x8 ET-3 with 205/50 Toyo Proxes R888R tyres...
I couldn't have had better fitment on the rear if I tried! The suspension might need to be taken up a tad as the clearance is very, very tight, but with no rear seats I'm not too worried.
I guess with the E21 rear trailing arms I must be close to ET-10 on the rears...
I don't know about anyone else but I always feel the wheel fitment and choice of wheels always sets off a car build in my mind 🤓