Michael Benno

I've been casually looking for a set of Cup I wheels for my 928 S4 for a little while now and some came up for sale locally. I went and looked at them tonight but I cannot find the Porsche part numbers on them so it's difficult for me to verify. The wheels are sized:

- Front 7 1/2" x 17" ET23
- Rear 9" x 17" ET15

Those offsets seem really off from what I am used to seeing on Porsches and don't match up to the listing I have for Cup I wheels:


So, I am wondering if that is really the offset or is there another way offset is measured and represent? I realize the correct offset for the 928 in these sizes is ET65 front and ET55 rear, so if these are the actually offsets measured the traditional manner, I doubt they would fit

Do you think these wheels are OEM or Replicas? They share look like OEM, although I have never seen polished faces. If they are OEM, what car were they for?

(unfortunately I am not able to upload any of the photos, the feature on rennlist just stopped working for me)

FredR

They're not OEM if those offsets are correct- that you cannot find a part number supports that. Porsche are not the only manufacturer that uses the 5x130 bolt pattern.

If those offsets are correct you should be able to tell just by looking at the wheels as the hubs will be well set into the rims as opposed to being at the outer edge of the rim- a characteristic of a large offset.

Eplebnista

If the width and offset are not cast into the rim next to the valve stem hole and there are no Porsche part numbers on the backside, they are aftermarket replicas. Likely Mille Miglia or a Japanese manufacturer. Some say that Mille Miglia used a special alloy employing salt water taffy as a constituent. Those offsets wont work for you in any case.

Much patience and a fat wallet are requirements for finding Cup 1's with an acceptable offset.

Michael Benno

hacker-pschorr

ET23 is correct offset on the front of an 80's 911 and maybe the model after.

puyi

Hi Michael

Clearly, you have replicas. As Hacker-Pshor said. The offset is correct for 80's 911 but not at all for 928, specially for the front wheel.

jcorenman

Michael, In the first two pics the centers are definitely pushed towards the outside, suggesting the large offset (ET) which is needed for the 928. However the pictures of the backside show that the center is very deep, pushing the mounting plane back towards the center. It's a dumb design, why push the centers outward (which looks bad in my opinion) but then add more material to the inside for a small ET? I suspect they did that in order to fit a variety of applications, by machining the mounting surface and drilling and boring accordingly. However once drilled they are done, and cannot be modified for a larger offset.

What you want are the Porsche factory wheels used for the 92-93 GTS, ideally without provision for RDK pressure sensors. The part#'s are 965-362-124-05 (7.5Jx17 ET65) and 965-362-128-00 (9Jx17 ET52). They will have the width and ET molded on either side of the valve stem on the outside, and the part# on the backside. Check this recent post from Rob: https://rennlist.com/forums/928-foru...l#post14586081

Sunset shows them still available, less than $4K for the set...

Michael Benno

@All, thanks for the quick replies and confirming these are replicas, as well as, confirming that the offset on the wheels is correct and, subsequently will not work on the 928. I'll let the seller know I am not interested.

x98boardwell

Yes replica's. They may have been replicas and made for the 964 Turbo's which have either the same or similar offsets to what you are showing. Those Cup I's came on those cars as well 91-93 964 Turbos.