dpepin

Hi everyone,

I am looking into buying some Cup1 to fit on my 1990 964 Cabriolet but I must say that the offset part is mixing me up. I did search the site but I have yet to come up to a post that describe how to see if a particular offset will work or not.

Anyhow I found a nice set of Cup 1 that I am interested into and needed to know if they are going to fit or not on my car, the wheel specs are as followed:

Rim specs for rear is 9J X 17H2 ET 47, front rims are 7 1/2J X 17H2 ET 52

Rear tires are 255\45ZR17 98Y , Front tires are 225\45ZR17 90Y

Thanks,

Daniel

Rocket Rob

Daniel,

I have Cup1's on my C4 cab. I have OEM 7x17 ET 55 and 8x17 ET 52 with 205/55x17 and 255/40x17. My car is lowered and I did not need any spacers. I suspect you should be fine with the wheels you describe.

Note: The factory wants you to install different stop blocks on your steering rack, if you change to 17" wheels. This is to prevent rubbing on the front wheel well.

crg53

Those are the exact dimensions of the wheels on my car, they are aftermarket Mille Miglia and the fit is perfect, my rear tires are 255x40x17. It is my understanding that the CUP wheels were 7x17 and 8x17, so chances are that the wheels you are looking at are also aftermarket.

nidon

I have OEM 7x17 ET 55 and 9x17 ET 55 with 205/55x17 and 255/40x17 on my C4, car is on bilsteins with eibach springs. No problem at all with fitting or rubbing front or rear, have also fitted 5mm spacers on rear to fill out arches Believe et47 on rear is no problem either (most replica cups are this size I believe).
Note that your tyre sizes seem wrong, this can be critical on a C4.
Front I believe are acceptable replacement size to retain rolling radius, rears however seem wrong, this is critical on a C4.
there is a caculator somewhere, (can't seem to find it at present) to work out difference in radius to see if it's acceptable

wit007

Definitely looks like aftermarket. I think few mm's of ET is not a big problem. But a problem could be with tires size - if you've got C4 difference in rolling radius is to big.

Computamedic

The rear tyres should be 255/40 not 255/45. I suspect a typo in the original post. Otherwise everything is fine - offsets are ideal.

Dave

dpepin

Thank you all for the info.

Here's a link to a wheel offset calculator

http://www.1010tires.com/WheelOffsetCalculator.asp