> Hey Walt....
> When you mention the 7.5x17/65mm offset wheels, are these "genuine" or the generic aftermarket copies of the 993/Cup2 wheels ???
They're the real McCoy.
> If they are factory Speedline, I'd appreciate the part number for these! I don't know about Speedline, I thought the real ones were made in Italy. I have the part number written down somewhere, now I just have to find it.
>When you mention the 7.5x17/65mm offset wheels, are these "genuine" or the generic aftermarket copies of the 993/Cup2 wheels ??? If they are factory Speedline, I'd appreciate the part number for these!
993.362.124.05 - from the GTS don't know if they're actually made by Speedline, but they are Factory 7.5x17/65.
> Ed, where did you find a genuine 993/Cup 8x17/70 offset? The only ones I've seen have been 7.5x17/65 offset.
Part # 993.362.126.01 used on 96-up Targa and 98ish Carrera RS
> Or did you just forget the real size, what with not having seen your GT in a few days....?
Not gonna touch that one :-)
There were the Carrera Cup Wheels, from the back of the 911/964. They are 9.5 x 17, 68 offset. Just the specs I wrote about way back in '91 in my PROJECT 928 series. Use 'em on the front as is, and with the GT spacers on the back. A little heavy for my tastes, about 27 pounds...as I later pointed out in my wheel and tire story, about five years ago. If you gotta have that specifc look, it's the best answer. Oh, these were one of the wheel sets recommended in for the 928 GT CUP in Germany, and was part of the published specs. It was nice to have them confirm my specs a few years later! I've faxed all this stuff to DEVEK, and Marc is going to publish all this data on their website, coming soon...under the heading "Alignment Rack." That way everybody can see where we were in the early to mid-90's, and that the factory's own work on the 928 for track use...which was all done separately, of course...is congruent. Hope this data helps! Kim
The return of the great Wheel Question. Let's get the facts out
(again.) Every 928 ever made came with a 65 mm offset front wheel, and
were 7's or 7.5's (of various diameters.) The exception? A few '89 928
GT's which had a 60 mm offset front wheel, which is also the only 8" wide
wheel. (That's the Club Sport 16" forged wheel, the last of the forged
wheels from Porsche for the 928, and it still only used only a 225 tire.)
The rear wheels range from 7's to 9's, with offsets ranging from 65 to 55 mm. Tires from 225 to 255. (Sometimes with a spacer.) So the rear is always easier to fit, the front is always the difficult fitment.
always check for the front wheel first! Who cares how many rears you can
find (that don't have a matching front that will fit properly?)
As I wrote in my wheel and tire story in PANORAMA back in December '97, as soon as you apply that 60 mm or more offset criteria, there are very few wheels to pick from. All the other Porsche models use a strut suspension upfront, (unlike our more advanced double "A-Arm suspension) so they go "out," not "in" like we do, when looking for wider wheels. This "thread" actually goes back to the PROJECT 928 car (in PANORAMA in the summer of '91) when I made 9.5 wide front wheels that fit (68 mm offset) when all the 56 mm offset 8.5's didn't work! (Tire rubbing on fender.) The factory later confirmed this with those exact rim and offset when doing the 928 GT Cup stuff for the German Porsche Club. (They used the 9.5 x17, 68 mm offset cast REAR wheel from the special Carrera Cup racecar...very heavy and not inexpensive, confirms the specs, but not a great "answer.")
The technical data has been published by me a couple times, and apparently
is treated as an "inconvenience," in that it eliminates the vast
of inexpensive Porsche 130 mm bolt-circle wheels, there seems to be a lot
of resistance. When I took copies of the Factory 928 GT wheel specs to
the big SEMA aftermarket trade show, (in '95) to give out to various wheel
companies N/C...in hopes of encouraging better 928 fitments...I was
practically thrown out of a lot of booths...many obviously didn't even
want to "know." "Caveat-empor!" And any pretty
"side" pictures on a
website don't prove that it really fits properly! I usually get a phone
call like this: I just got a good deal on some 993 (or you fill in the
blank on some jazzy late style wheels) what kind of spacers do I need Kim?
My answer? How good are you at spacing IN? Cause that's what you'll need to do with that 52, 55 or something like that offset front wheel. Usually there's a big silence after that. Save yourself from the same mistake! Mostly what it boils down to is that the only way to get big tires on a 928 is aftermarket multi-piece wheels. Yes, they are more expensive than all those cast 944/911/Boxter wheels. AND you can get them custom, so they actually fit! Like? 265's (F) and 285's (R) eighteens on a 928S4/GT. Without rubbing the fender lips. A nice set-up for a late model 928 S4 or GT. Those are real Porsche sizes (from the back for the C2 Turbo and C4 Turbo respectively.) go through a zillion questions with various 928 owners, apparently still hoping to find an exception, those one set of inexpensive one-piece wheels that's going fit. They spend hours, and days on it. You can search all want...they're all wheels for the other Porsche models, being presented as "for a 928." NOT! As such, since you know their front offsets don't match those of a 928 stock, they really don't fit a 928, least of all when we're trying to maximize the fit in the wheel well! As far as putting bigger wheels and tires on a 928 (like the set-up I mention above) it isn't going to happen that way! Save yourself the wasted effort. Forgeline, OZ, HRE, Kinesis, RD Sport...they can all build what you really want! Get forged centers, while you're at it! Having fender-rubbing set-ups, while you can get your fist between the wheel and the coil spring on the huge clearance on the inside... now that makes absolutely no sense to me! 65-68 mm fronts and 52-60mm offset backs... that's what works, unless you have flared fenders! (Which makes the rear of the GTS the one exception.) DAAAAA, using the factory offsets works, moving it out a lot doesn't. Sorry, I can't change the laws of physics or economics!
The great 928 wheel debate. And the simplest answer to the "I want some cheap
wheels to update my 928" question is "no." The 928 had 65 offset front wheels
for it's whole run, from '78 through to '95. Very few Porsche wheels had that
high an offset. Ultimately what that means is that while you can occasionally "fudge"
and run 55 mm offset front wheels...but then you have to stay with narrow tires
or you WILL rub the fender lip. For me that occurs as a "why bother" then? This
all got into
"high gear" when I did PROJECT 928 in PANORAMA back in '90-91. I
discovered that nearly all the aftermarket manufacturer's (who I suspect copy
each other) improperly list that 928 specification. I got some 56 mm offset
8.5's and they rubbed with only a 235 mm width tire, with the car modestly
lowered. Making that into a 68 mm offset 9.5 (with a one inch wider "Inner" rim
half) fixed the problem. Why? The tire tread shifted over when the inside rim
edge was moved, and that extra clearance was sufficient. I often find when
discussing this people overlook that they really need to know where the tire
tread is...not the rim edge. Given that tires only nominally fit the printed
size, there is an allowed 5% legal variance, this becomes a nearly unworkable
problem for mere theory if you're experimenting close to the fit limits. Of
course, many wheel vendors want to sell their 944 and 911 stuff to 928 people.
they have in stock. Caveat emptor. After the publication of PROJECT
928, one Panorama wheel advertiser tried to have me removed from the Tech
Committee. So wouldn't expect them to come clean anytime soon. In '94, when the
factory published the 928 GT Cup specifications I had hoped this would all be
settled. Why? They had the absolutely identical 9.5" wide
68 mm offset front wheel specifications I'd advocated four years earlier.
With the factory now publicly agreeing, what more proof could anybody want? You would think this would settle this once and for all? Judging from the re-occurance of this particular question on the list, evidently not. In the nearly 15 years I spent taking volunteer questions on the 928 for PCA, and "meeting" a lot of great people from all over the USA, sometimes it did come down to this: we figure how to do anything you want, but I can't necessarily make it cheap. Sorry. Kim
> My Porsche 993 (Cup) wheels are: 8"x17" with a 70mm offset,
and the rear
> wheels are 9"x17" with a 55mm offset. YMMV.
Ed, where did you find a genuine 993/Cup 8x17/70 offset? The only ones I've seen have been 7.5x17/65 offset.
Or did you just forget the real size, what with not having seen your GT in a few days....?
My Porsche 993 (Cup) wheels are: 8"x17" with a 70mm offset, and the rear wheels are 9"x17" with a 55mm offset. YMMV.
I'm looking into replacing a tired set of flat wheels on the 928 I just recently purchased. In perusing the used market, I have a line on the following:
These Design 90s from a 968:
6J X 16" 964.362.112.01
8J X 16" 964.362.116.01
And a set of five-spoke C-2 style wheels previously run on a 993.
Can anyone tell me if there are fitment conflicts with these, or if a spacer is required? Trying to get something a little sharper without entirely breaking the "immediate needs" bank (which is already in deficit mode!)
1983 Euro S 5 spd
Can't recommend 6" wheels for a 928! Also, the usual problem with trying to use wheels from another Porsche model on a 928 is trying to space the front wheels "IN!" If you can do that, please let me and NASA know how! Sorry to bring you the "probably gonna cost you a bit more money" news.
Somehow, it seems the calculations regarding wheel sizes turns into greek rather than basic math for me, so I'm seeking the expertise of the list...
I've located a set of 17" (7.5 and 9) with an offset of 44mm. Will these fit my '89 S4? I'm planning on putting the "standard" 225/45 and 255/40 on there. BTW - as far as I can tell, the new tires will have (close to) the same width as my old tires (225/50-16 and 245/45-16) - how come the recommended widths for the larger width new rims aren't wider? I would have thought one of the benefits of the wider rims would be wider rubber? Also, on my 944 CAB I'm running "plus 1" on the tires - is that possible / recommended on the 928?
Thanks and Happy Motoring,
The tires will fit the rims, but those rims with a 44mm offset will cause both front and rear tires to stick out beyond the lip of the fender. BTW, spacers will only make matters worse.
If you want rims that work without having to do any bodywork, the wheel offsets for your S4 should be about 62mm for the front and about 50mm or so for the rear. YMMV.
~ Merry motoring ~
>From: "Paul Diedrich" <firstname.lastname@example.org> I purchased the car last May and it came with what I believe are the Kinesis Supercup wheels - though with a Porsche crest instead of a Kinesis crest on the hub.
>The current set up is:
>Is there anything "wrong" with the current set-up?
Sounds like the Kinesis setup 928 Specialist sells. 9" front wheels and 10" rear wheels. Very nice setup! Can't wait to put them on my GT. Keep those size tires and get the car set at the proper ride height and aligned properly. You will be pleased.
Good to hear from you , we haven't seen you in the 928 world lately. Hope is well with you and yours.
>The great 928 wheel debate.
More like the great 928 wheel "compromise" :-)
> And the simplest answer to the "I want some cheap wheels to update my 928"
question is "no."
> The 928 had 65 offset front wheels for it's whole run, from '78 through to '95.
FYI, your 89 928GT came with 60mm offset fronts
> Very few Porsche wheels had that high an offset.
True, but that trend seems to be changing, check out the offset on the 997, they are getting close.
> Ultimately what that means is that while you can occasionally "fudge"
> and run 55 mm offset front wheels..
Or even 52mm
>.but then you have to stay with narrow tires or you WILL rub the fender lip. For me that occurs as a "why bother" then?
False statement, you have to stay with the PROPER size 928 front tire for that width which would be a 225, same as used on the all 16 & 17 factory wheeled 928s (same goes for 18" aftermarket).
I know of thousands of 52-55 mm offset front 928 wheels running the proper 225 tire that have no rubbing , even when lowered with in reason.
> I discovered that nearly all the aftermarket manufacturer's (who I suspect copy each other) improperly list that 928 specification.
No, they don't "improperly list" the spec. What they do is make a "compromise spec" that enables them to make one offset wheel fit more than one car. This is not optimum or necessarily the right thing to do, just pure economics. IF the replica manufactures had to make a specific wheel for only a 928 they would not (and don't) bother because of the very limited market.
If they didn't make this "compromise" multi-fit version 928 owners would only have the choice of expensive factory or custom made wheels.
> I got some 56 mm offset 8.5's and they rubbed with only a 235 mm width tire, with the car modestly lowered. Making that into a 68 mm offset 9.5 (with a one inch wider "Inner" rim half) fixed the problem.
FYI, you should have been running 255s with a 9.5, most manufacturers do not recommend over 9" for a 235 (which BTW, is a size not designed for a 928, too tall)
> Of course, many wheel vendors want to sell their 944 and 911 stuff to 928 people. It's what they have in stock.
"Stock" is not the issue, manufactured is the issue. There is not a vendor that sells wheels for a 928 that would buy 944 wheels for 928s, IF there was an option in the price range that the majority demands.
> In '94, when the factory published the 928 GT Cup specifications I had hoped this would all be settled. Why? They had the absolutely identical 9.5" wide 68 mm offset front wheel specifications I'd advocated four years earlier.
But with a 255/40-17 , not a 235!
>With the factory now publicly agreeing, what more proof could anybody want?
What is there to agree with, offsets for a 928 are not magical numbers created by you or anyone, they are dictated by pure math. A 10 year old with a tape measure can figure out the proper backspacing for a wheel on any car. No brainier, BUT getting the manufactures to make it is another story.
> You would think this would settle this once and for all? Judging from the re-occurrence of this particular question on the list, evidently not.
I don't think any replica or aftermarket one-piece wheel manufacture doesn't know what a 928 needs, they just know that a 928 needs a special wheel and they can't make the economics work for them to make a one-piece cast wheel for such a limited market. Hence a workable compromise, Plain and simple. Trust me I have tried for many years, I consider us lucky that they at least make a compromise wheel that most of us are happy with.
> In the nearly 15 years I spent taking volunteer questions on the 928 for PCA, and "meeting" a lot of great people from all over the USA, sometimes it did come down to this: we figure how to do anything you want, but I can't necessarily make it cheap. Sorry.
True, we sell Kinesis, Fikse, Forgeline and HRE who make them for use to the specs we want, I sell and use up to 255/35-18s with 9.5 fronts and 295/30-18s with 11 rears for later street 928s and have no rubbing issues at all.
BUT, there are many 928ers that cannot budget for that expensive of a wheel and want to upgrade the looks of their 928 and the one-piece replica "compromise fit" wheels we (and others) sell work very well with out any issues. Sure they are not perfect, but they are not really wrong either, they just may not be "right" for some people.
>I am with Kim on this one,
I think we all are about the correct offsets.
>I did have the replica wheels on my 89 S4 when I bought it and switched to the 89 GT wheels. The steering feel, and the tracking ability of the car changed for much better.
That is kind of ironic, the 89 GT front wheel is 8" wide (which is part of the reason for the better feel), and a 60mm offset, BUT if you take a 1/2" off that front wheel it becomes a 7.5" wheel with an approx. 50-52mm offset (Long day, but I think my quick calc is close).... VERY Interesting!!! The 89GT Factory Front wheel sits almost identically in relation to the fender lip as an inexpensive replica wheel does (in my experience the 89GT wheel sticks out slightly farther and closer to the fender lips). Porsche was already on to something with widening the front and rear track even back in 88 to make them handle better...but still with a 225 :-)
Bora, If you like the 89GT wheels we need to get you into set of the Factory 9.5 x17s with 68 offset at all 4 corners. You could run 255s all the way around and since you already have the 89GT spacers you would be good to go. Direct bolt-on fit and Genuine Porsche wheels! You could even rotate your tires at all 4 corners to maximize wear if desired!
>I do have to say that I am a BMW club racer and probably more sensitive to steering and brake feel than the average street driver.
Once you start driving a 928 in anger with at least 255s on the front you just might become a 928 Club Racer instead..... and forget that Bimmer:-)
The example of the 60 mm offset '89 GT wheel is poor. The factory had to
"cringe the folds" (as they call rolling the fender edge) on the fender lip to
fit the same 225 width tire. All about 100 cars worth. All the rest are 65 mm
offset...the other 56,000 cars. And the GT Cup specs are clearly for a 68 mm
offset front wheel. Which is what I used back in '90 and...for the record...is
what's on my '89 GT (yes, its' still down with
#2/#6 connecting rod bearing disease, so don't expect to hear about adding to
any of that long list of winning results any time soon.) Oh, here are the
specific widths and offsets I use:
68 mm offset 9.5" front wheel
52 mm offset 9.5" rear wheel
You can run 255's, or 275's, depending on what the rules allow...
The front wheel is always the hard spec to meet, of course. I may just "get out my dremel" as you suggest. As PROJECT 928 proved in many ways nearly a decade and a half ago, this "shortage" only goes on until somebody gives up being resigned about it, and instead gets on with it.
997 18 inch wheels have 57 mm offset front (18x8) and 58 mm offset rear
Will these work in my 928 S4 (1989)
I'll give you the "short" answer.
1- rears should fit fine (and probably use 285/30/18 tires)
2- fronts have too little offset for best fit...since the wheel is moved out towards the fender (where there is the least clearance in the first place) you probably can "use" them IF you don't increase the tire width.
You end up using a 225/40/18 tire. Given the weight distribution, that might make sense for a 911...but a 928? I'd much prefer a 255 or 265 (35 series aspect ratio x 18) on the front to balance that 285. That takes a 9 or 9.5" width front wheel. And that takes a 65-68 mm offset front wheel to get fender clearance (it's more like the stock offset, too.) Perhaps that lays out the issues. The difference between "will it bolt on?" (Yes.) And is it an excellent fit? (No.) Really...when you think about it...given the radical difference in weight distribution between the 911 vs. 928, how likely is it that there would be a really effective interchange of these parts? YMMV. Kim