10J x 18 ET58 - someone with experience please

[Gary H]

Hi all

After spending hours with various offset calculators I'm almost there, but would really like someone's advice, who's done it:

I've just bought a set of Carrera III alloys:
Fronts: 8J x 18 ET 57
Rears: 10J x18 ET58

My current Turbo twists are:

Fronts: 7.5J x 18 ET50
Rears: 9J x 18 ET52

The car is a 2001 Boxster 986 3.2S

What I'm trying to work out is the size of Spacer required at the back - I currently have a 22mm and whilst it easily clears the strut, the tyre does stick out of the arch slightly.

The research I've done suggests a 15mm or an 18 mm spacer will be perfect, but not having the luxury to try before I buy I don't want to make a mistake and I'm finding mixed results re. rubbing - whilst the 18 will definitely work, will the 15 tuck in slightly without rubbing on the strut? I'm getting confused!

Cheers