Yes, the hub is identical
Same 4x100 PCD and same 57.1 mm centre bore: wheels from Seat Mii bolt on and centre on BMW 3 Serie E30 without rings. You still need to check the offset and tyres, detailed below.
≈: width estimated from the original tyre size.
Wheel by wheel: offset and tyres
Each original wheel from Seat Mii is compared with the one from BMW 3 Serie E30 of the same diameter: how much closer the wheel gets to the shock absorber or how far it sticks out of the wheel arch, and whether the tyre keeps the same overall diameter.
- ✓
5Jx14 ET35 · 165/70R14 — Fits like the original
Compared with the original ≈5.5Jx14 ET35 on BMW 3 Serie E30: shock absorber side −6.3 mm, wheel arch side −6.3 mm, tyre diameter −2.3 % : fit it with the original tyre size of BMW 3 Serie E30 (175/70R14), not that of Seat Mii.
Comparison for guidance only (estimated width). Check in detail
Before fitting the wheels
An identical hub is not enough: offset, width and diameter change the position of the wheel, and larger calipers can touch a smaller wheel. Original wheels often use bolts or nuts with a specific seat: keep the fixings intended for the wheel, with the thread of BMW 3 Serie E30 (M12x1.50), tightened to the torque shown on its vehicle page. Finally, check that the size is among the approved fitments for your vehicle. This comparison is for guidance only: have the fitting approved by a professional.
And the other way round: wheels from BMW 3 Serie E30 on Seat Mii?