ScottyB

Will a set of 17" "cup" wheels from a '95 993 fit on my '90 C2? Thanks for the help.
Scott

Michael W

Hi Scott,
Below is a link to an earlier post on your question.
http://forums.rennlist.com/scripts/rennforums/ultimatebb.cgi?ubb=get_topic&f=4&t=000430

I currently have 17" wheels on the '91C4 off an '97 993 targa.

17" is a popular upgrade, pay attention to the wheel offsets.


I hope this helps

Mike

Adrian

Dear Scotty,
You "MUST" check the rear wheel offset and the wheel width. These 17 inch wheels will most probably (if genuine) be 70mm offset 8JX17 wheels. What are called "Winter wheels" here in Europe. These "WILL NOT" fit properly unless you use 15mm spacers on each rear wheel hub.
The fronts are 55mm offset and as long as they are 6JX17 or 7JX17 no problem. If the rear wheels are 55mm (which in 1995 they were not) then as long as they do not exceed 9JX17 you are okay.
One thing that you need to look at with wheels and tyres and quoting "Of a 1995 993". You need to check if these wheels are really "originally installed wheels" or a "POs modifiation".
Ciao,
Adrian
911C4

PS: I have already been contacted and helped out a few people with exactly this issue. There are a few sets of these "Winter Wheels" from 1995 floating around on ebay andbeing sold privately. There is nothing wrong with them as long s you understand that they do not just bolt on "have no problems" on a 964 at the rear.

ScottyB

Mike and Adrian,

Thank you very much for your help. I will print this information out and take a look at the wheels myself.
Kind regards,
Scott

Jeff Curtis

Adrian, by all means, correct me if I'm wrong...but in my latest adventures in converting to 17" wheels for the track, I have discovered that only the 16" 993 wheels have a 70mm backspacing in the rear. The Cup II wheels in 17" have a 55mm backspacing, from the factory.

ScottyB, to answer your question, all 17" wheels from a 993, 996 and Boxster will fit your 964, I have all three types, Turbo Twist, Cup II and the 996/Boxster S "Twist" wheels, the latter I use for the street, the others for track wheels...in all sets, the rears are either 8.5"/9" and 50mm/55mm backspacing respectively.

What I have found is using the 9" rear wheels and 55mm backspacing, the 275mm rear track tires I use tend to rub a little on the trailing arms and the oil line on the passenger side under heavy load. This has been remedied by a 6mm spacer...with steel lug nuts for the track, there is just enough thread to pass PCA Club Sport guidelines...although I plan to install slightly longer studs this Winter.

The 996/Boxster "Twist" wheels I use for the street are 8.5" in the rear, 50mm backspacing with a 255mm tire, no problem there at all...I would expect the same results with a rear 9" wheel and 50mm backspacing. It is when people want to use a 275mm tire in the rear where they experience some rubbing.

Adrian

Dear Jeff,
I am afraid your statement about the 17 inch wheels is not correct. In fact I posted many moons ago the part numbers of these wheels. They are known as winter wheels and they have an offset of 55mm front and 70mm rear. These wheels are to be found in the USA, I know I have helped a couple of USA owners out who were unfortunate enough to purchase them.
I do not have the time right now to check part numbers but they have been posted and can be found in the archives.
"Check" the number by the air valve. Post 1995 models was when Porsche introduced 55mm offset on the rear of the 993. 1994 and 1995 had 70mm offset with 16 inch wheels as standard,
Ciao,
Adrian
911C4

PS: These wheels were an option as well.

Jeff Curtis

...whiiiiiiiich basically brings me back to my original statement, "only the 16" 993 rear wheels had a 70mm backspacing".

Although...I do >seem< to remember seeing a set of CupII wheels in 17" that had the 70mm backspacing on the rear...most all I found for sale were the 55mm backspacing...so that made me believe that I was possibly imagining things? Guess not, thanks Adrian...I was beginning to worry!

Adrian

Sorry Jeff you have lost me.
1994 and 1995 993s have an offset on the rear of 70mm. The 16 inch (standard) and 17 inch (optional) wheels are 70mm offset.
These 70mm offset rear wheels require 15mm spacer to be installed on the rear of a standard 964.
In 1996 model year, the 993 was changed to a 55mm rear offset.
You will find many 993s from 1994 and 1995 with 17 inch 55mm rear wheels. However these were not original. Instead of using spacers to fill in the rear arches they just install 55mm offset wheels. The vast majority of 17 inch wheels on the market, new and used are 55mm and this is why I always mention these other 70mm ET wheels, because I know of at least four people around this list who have been caught already,
Ciao,
Adrian
911C4

ScottyB

Thanks again, guys, for the information. I saw a picture of the wheels and they look pretty nice. Here are the sizes the owner reports - said they came from a 95 993. Will adding the 15mm spacer affect the handling and or safety of my car?
Scott


"The fronts are 7Jx17 - ET55 with a backspacing of 6" or 150 mm.
The rears are 9Jx17 - ET55 with a backspacing of 7" or 180 mm."