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Correct 17" Wheel Offsets?

Church

Church

New member
Ok I know this has been done to death in the past - HOWEVER looking at previous posts there appears to a difference in opinion.

What are the correct (as in the Cup1 Mags) offsets?

Most old posts state

Front 7.5 x 17 ETA 47
Rear 7.5 x 17 ETA 55

However others state the front offset is 55, so which is correct OR are some 47 and others 55 on the front?

I've tried checking my original wheels but can't see any numbers which resemble the ETA, where should I be looking? They have been refurbished perhaps thats the issue.

The reason for asking is I'm looking at getting BBS to make me some 17" Mag. Wheels and I'd like to quote the correct offset.

Thanks
 
For Porsche 964RS lightweight

Front 7.5J x 17 ET55
Rear 9J x 17 ET55

Reference: Porsche PET catalogue


I have 17mm spacers fitted for the rear pair

Hope this helps.
 
Church,
I've got a set of 17" BBS Mags. They are 7.5 ET 55 and 9 ET 49. Apparently ET 49 is the closest they can do to the factory ET 55. It is just the same as running a 6mm spacer, so they bolt straight on without any problem. Indeed you could probably run up to a 15mm spacer on the rear if you wanted to push the wheels out, and still be ok.

The problem you have though is that the Mag wheel centres don't have recesses to go over the nuts on a bolt-on spacer, so you need to run a shim instead, and for anything bigger than about 6mm you need to use longer wheel studs. For the sake of simplicity I just use a 6mm shim on the standard rear studs, which is effectively the same as running a 12mm spacer with standard wheels. This means that I can interchange between Cup 1s and the BBS without worrying about wheel studs (I do use bolt-on 16mm spacers with the Cup 1s though - just have to replace them with the 6mm shims when I put the BBS on for trackdays).

Hope that helps !

Jamie
 
Jamie,

If I remember correctly you beat me to the 17" BBS Mag wheels when they were being sold by jimmyslr.

I currently use a spacer (18mm) with my Cup 1's on the rear but I'll probably do as you have suggested and interchange this with a 6mm shim if I go for the BBS wheels.

How are you getting on with them? Are the Ali rims a wheel pain to keep clean? If I remember the front wheel centres protrude slighlty is this correct? Do you have any pictures of them on your RS?

Thanks,
Paul
 
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