Mag Cup Wheels

[bobster]

Hi it's the new 964 boy again.

I know the subject of Cup wheels and spacers have been discussed, but I cant' find anything definitive to this issue.
Whilst checking my new car over for an MOT I noticed the front LH tyre has been contacting the inner wing on LH lock and worn through the underseal. The RH front has just left the slightest witness mark in the road dirt in the same place obviously from RH lock.

My car's Not an RS, but has Magnesium Cup wheels 7.5Jx17 ET55 Front & 9Jx17 ET55 Rear and from what I've read these are correct and standard Cup wheel sizes. The car is also lowered 30mm, (if that makes any difference to this touch condition).

I'm wondering if these wheels should be used in conjunction with spacers or do I have a geometry problem?
I'm guessing that something like 5mm spacers might solve the problem if it's not geometry, but if I go that route would I space the rears by the same amount to retain the front to rear track relationship, and if I do that, are the studs long enough or would I need to change them.

What does an RS run with these wheels? If the answer is spacers, and if they are more than 5mm and I went that route, would the standard geometry stay?

I hope there's not too many questions here, but I'm assuming that as it is, it would be an MOT failure. Even if not I need to do something.

Many thanks,
Bob.

 

[Stewart H]

The RS is 40mm lower than the standard car and has aluminium wheel carriers together with rolled wheel arches. IIRC, the rim for a C2/C4 is 7" rather than 7 1/2" so the overall set up is slightly different. The offsets for the RS are 55 front and rear which may differ from the C2/C4 (I don't know)

I know this doesn't answer the question, but it might be a combination of all of the points.

 

[964rh]

Bob

5mm spacers should solve the rubbing issue you have.

A few cars have this if they haven't got the 10mm steering stops installed (these were fitted by POrsche when they started putting 17" wheels on the 964)

After I had my geo setup to as near as RS as the C4 can go, mine still rubs. Never failed an MOT tho'

Offset should be 55mm front and rear on 17's

Rob

 

[Dave Wilkinson]

Bob,

Just to add to Rob's reply, the 5mm spacers will be fine with the standard stud length although that is the limit. The larger steering stops are the oficial solution but they do add to the turning circle considerably and you might feel the spacers are a better solution. As a new 964 owner I'd recommend that you get hold of a copy of Adrian Streather's book - Auftragsnummer 964, Enthusiasts Companion. It's pretty much a 964 "Bible" and you'll never be lost for an answer to questions such as this. It's proving to be a little difficult to get hold of now but they do pop up on eBay from time to time and I believe the publisher in the US (Bentley) can still supply.

Regards

Dave