markpaul

I'm potentially looking at a set of 18" Carrera III 997 - fronts 8x et57, rears 11x et51. My '91 S4 already has factory rolled rear fenders for some reason. My questions is - will these fit my car without any body work? Any help would be great. Hopefully someone out there has tried these wheels with this width and offset. Any tire advice would also be helpful if it looks lkike they will work.

PRC928

I have 11" rears from a 996TT with a 45mm offset and a 295. With rolled fenders there is no rubbing, so with a 51 you will have a little more room.

markpaul

Great, thanks Paul

FredR

Mark,

You question is conditioned by your use of the term "work".

If you mean "will they fit" I am reasonably sure they will. As to whether they will work is another matter altogether the potential problem being the front wheels. If you are not aware of the concept, look up Negative Scrub Radius to understand what it is.

Porsche designed your 928 to run with a 10mm NSR and to achieve this required front wheels with an offset of ET65. Most OEM Porsche wheels from other models typically have offsets in the range ET52 to ET57.

Reverse spokes are great looking wheels but to my knowledge none were ever made with ET65 [unfortunately]. There are some Cup 1 and Cup2 wheels with such offsets [other than GTS wheels] and finding something Porsche OEM with correct offset in 18 inch diameter wheels is very rare [impossible?] indeed.

We have had a few folks on the list who were not aware of what was going on until they tried wheels with the correct offset and then decided to ditch what they had previously been running. That being said many folks run around with wheels that have incorrect offset and are happy with their lot.

I once ran some 18 inch 911 reverse spoke wheels- looked great but performance wise could not ditch them quick enough [they are now where they should be- on a 911].

Porsche knew exactly what they were doing when they designed the 928 suspension. I would not run with less than ET65 but that is me - each to his own as it were. Just make sure you know what you are taking on.

When I was researching this concept many years ago one of the most interesting points I read was an authorititive opinion that a positive scrub radius was better than a neutral scrub radius that happens whe the wheels are ET55 which ironically is where many wheels that have made their way onto a 928 sit.

Bottom line if you are keen on performance driving correct offset is important, if you are not that fussy or do not push the car too hard then it is less of an issue.

Whereas it is possible to modify a Porsche specification and get improvement one needs to ensure one knows what one is doing or does so on the word of someone they really trust.

Regards

Fred

Mogans

Fred, you're making an important point. I am one of those running around with 50'ish front offset wheels. One of these days I'd like to get some wheels that are ET65 in the front, or at least a lot closer to that. It would be nice if there was a resource / specific thread that listed wheels / wheel manufacturers that offer offsets correct for the 928. Maybe it already exists and I am unaware, please let me know if that's the case.

FredR

Mogans,

The problem is that to get such offset requires a stronger wheel to carry the offset weight all things being equal so no one makes them economically if there is no market for them, then you get into the custom market wherein 3 piece forged alloys centres with bolt up rim sections effectively corner the market but at a price but then you can have wider rim sections to suit your needs so for instance my wheels [see my avatar] have a ET68 up front and carry a 9.5 inch rim section enabling me to run a 265x35 x18 section up front. For the rear I have ET60 x 10 inch designed to carry a 285 [or 295] x30x18. For a street setup the grip is phenomenal and mate that to a couple of degrees of camber up front and 911's are no problem in the bends.

Not too many owners are fortunate enough to experience this level of handling but it is quite astonishing when you get it right. On an autocross event they took 5 seconds off a 60 second lap.

If you want OEM type wheels Porsche do a nice Cup 1 with ET65 x 9 inch x 17 and that is about as good as it gets. There are also some winter wheels with high offsets [ET70?] but more std widths for the front I believe available in 18 inch diameter. Of course such wheels are rare s/h but they do come up from time to time- very expensive new. Alternatively there are the GTS Cup 1 and cup 2 wheels- again quite rare these days. Must get my set refurbished one of these days. The cat likes to sleep in them at the moment!

Rgds

Fred

Vilhuer

8" ET57 is only 3mm from CS, SE and '89 GT 8" ET60 Club Sport. Its basically closed possible without being exact same setup.

As for the 11" rears. They will work but its better to save them for GTS and use 10" versions on narrow body 928's.

85euro928

Use the 11"s and roll the fenders.
Just do a better job than I did

ShiftingGears

HELP!

One of my D90 rear wheel 16x9 52 is totally trashed and cannot be repaired. Cannot find a replacement.

The other 3 need restoration and new centre caps. The price means I might as well buy new wheels.

Cups look good. Can get them with 17 inch. Does that work or do I need to raise the rear a bit?

Some one get definitive for me please and say 'you should buy the following...'

SwayBar

IMO, you should buy 18's as they fill-out the cavernous wheel-wells of the 928 and helps balance its looks.

GregBBRD

Just keep in mind that 928's understeer....a bunch.
Changing the rear to a much wider wheel and tire will make the rear of the car "stick" even more....greatly increasing the understeer.

If you are just looking for "looks" and do not drive the car aggressively, you might not care.
If you ever aggressively attack corners, you will care.

As far as 17" or 18" is concerned:
If you live in a place where the streets are very smooth, the shorter/stiffer sidewalls of the 18" tires are not terrible.
If you live in a place with bumpy roads, 17" tires are much better.

Darklands

I have a complete D90 set in my barn.

The good tires are a present! ;-)

ShiftingGears

Many thanks for the wheels Karsten. A total replacement of the originals in good condition.