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964 offset questions

Old 11-08-2007, 09:19 AM
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Default 964 offset questions

Guys, I have done my homework but it seems to yield different answers.. I would like to know acceptable offset ranges on 964 NB and 964 Turbo cars. From what I have read:

964 NB:

Front 7x17 ET52 (Cup1)
Rear 8X17 ET47 (Cup1)

What would be acceptable ranges for, lets say an 18 inch wheel? (Given 8" front and 10" rear?)

Would this work?

Front 8x18 ET52
Rear 10x18 ET54

Basically what I am asking is, what are the tolerances, given 8" front and 10" rear?



964 turbo:

Front 8x18 ET52 (Speedlines)
Rear 10x18 ET61 (Speedlines)

I know for sure that this works:

Front 8x18 ET52 (993 WB hollowspoke technology)
Rear 10x18 ET40 (993 WB hollowspoke technology)

This is a variance of 21mm(!!). Is this the minimum offset (ET40) for a turbo given a 10" wheel in the rear. Are the offsets the same for 964 turbo front and 964 NB front? Are the offsets the same for 964turbo and 964WB coupe (anniversary)?

TIA guys
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Old 11-08-2007, 11:14 AM
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Strega(UK)
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Use this website, brilliant little tool for working out any offset's.http://www.1010tires.com/WheelOffsetCalculator.asp
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Old 11-08-2007, 11:42 AM
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Bill Verburg
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the 16" Design 90s were both 52.3 for 7 & 9

Cup1(aka Design92) in 17 were both ET55 for 7 & 9

for custom fits
the RoW Cups used 8x17 ET 52 & 9.5x17 ET 68 w/ a 21mm spacer for a net ET of 47.

Others have used 8x18 ET 52-56 front & 10x18 ET65 w/~20mm spacer in the rear. All will require some fiddling w/ oil lines, lips and suspension settings
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Old 11-08-2007, 11:50 AM
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joey bagadonuts
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Originally Posted by vhanzon View Post
Guys, I have done my homework but it seems to yield different answers...
Part of the reason for different answers is that there are a number of variables in addition to wheel width and offset, i.e. tire brand/model, width, outside diameter (tire height), spring rates and design (linear or progressive), static camber, ride height and road conditions.

I agree with Bill's numbers for a NB 964: front 52mm and rear 47mm
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Old 11-08-2007, 11:52 AM
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Originally Posted by vhanzon View Post
What would be acceptable ranges for, lets say an 18 inch wheel? (Given 8" front and 10" rear?)
This will vary by car.
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Old 11-08-2007, 12:19 PM
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Originally Posted by Bill Verburg View Post
the 16" Design 90s were both 52.3 for 7 & 9

Cup1(aka Design92) in 17 were both ET55 for 7 & 9

for custom fits
the RoW Cups used 8x17 ET 52 & 9.5x17 ET 68 w/ a 21mm spacer for a net ET of 47.

Others have used 8x18 ET 52-56 front & 10x18 ET65 w/~20mm spacer in the rear. All will require some fiddling w/ oil lines, lips and suspension settings
Thanks for the info guys. I realize that there are many factors in this.. I just want to know the ballpark tolerances.

So, if I understand you correctly:

8x18" front and 10x18" rear

964 NB front ET 52-56
rear ET 45-47

What are the same ballpark figures for the turbo and WBs?

Basically I'm curious to know which 993 wheels will also fit a 964 . Then if you have two cars (993+964) you can swap wheels back and forth. The figures for the 964 coupe as stated above basically means that any set of (8+10x18) wheels that fit a 993 NB coupe will also fit a 964 Coupe (with the correct rear spacers). Fronts are the same (8x18" ET52) so they fit bolt on and the rears for the 993NBs are typically in the ET65-55 range, which means that they can be adjusted to an effective ET of 47 with the proper spacers . Good to know!

Not sure about the WB 964s though.. I have yet to find out.
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Old 11-08-2007, 12:41 PM
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I have 8.5x18 and 10x18 on my car with 225/40 and 265/35 respectively. In the rear, the wheel has an offset of around 40 and I use a 3mm shim plus a hammer to the oil line to ensure I have enough clearance. I think 47 is too much in the rear - but it does vary from car to car even (if ever so slightly). I would suggest that if you go for a 10 inch wheel that you aim for around 40-42 - I think 47 will cause some problems with your oil line potentially. In any case, please remember that if you use some massive spacers (or basically anyuthing over 6mm) that you use longer studs to make sure your car retains the wheel in the correct location - i.e. attached to the car. That is a safety requirement for 6mm+....
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Old 11-08-2007, 03:13 PM
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I have 993 turbo twist wheel on my 964. 8.5 x 18 front and 10X18 rear. Tyres are 225 front and 265 rear. the front ET was 52 and the rear was 65 et with a 17mm spacer on the rear to give me 48 et.

No problems with clearance. Oil line is flat. I had played with spacers in the rear, went from 15mm with slight rubbing issues on the inside fender walls to 17mm that cleared everything, no rubbing at all.

15mm should work on most cars, but you may need to get the car aligned correctly to make sure there are no rubbing issues. 17mm works for me.

Tyres do affect the rubbing issues so despite the ET, the tyres will change the offset on the rear. 17-19mm should be enough regardless of tyres.

My spacers came with the studs.
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Old 11-09-2007, 09:21 AM
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Thanks for the feedback guys. Christer, you are saying that your rear 10x18 ET40 was a direct bolt on? I thought ET40 was too close to the fender wall? Southampton: Do you have another 7mm outer clearance? Since you are at ET47 now, do you think you would be able to push it to ET40? Maybe with rolling fenders? Ofcourse suspension settings and tire brand etc will play a big part of it all..
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Old 11-09-2007, 03:43 PM
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I doubt it. I tried 21mm spacers, that took me to 44et and they rubbed the outer fenders, badly.

No idea if you rolled the fenders if you they would fit. I would try and stick to close to 47et.

Here is one other consideration. At 47et the tyres on the rear DO stick out from the rear fender close to the bumper, when it rains, I get a LOT more spray up the back.

Cops in New England don't like that!!!!
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Old 11-09-2007, 04:31 PM
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I have ET47 on my rear 10x18 wheels on my 964, and the car is lowered 30mm and has rolled fenders. In the front i have ET52 and 8x18.

Regards

Per
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Old 11-09-2007, 05:02 PM
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Ok thanks all.. That pretty much answers my questions. How streched the tire is on the wheel itself will also affect the rubbing issue. However, a 265 tyre on a 10" wheel is already stretching it so stretching it more is not an option. I guess you would have to stick to an ET around 47.
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Old 11-09-2007, 06:09 PM
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Not sure why you want to go wider anyway. 10" on the rear is fine with relevant spacers. I have bridgestone potenza pole position tyres. thats 20"+ of rubber back there!
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Old 11-09-2007, 07:31 PM
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I don't particularly want to go wider. I have a set of 993 technology hollowspokes lying on the shelf and I was just wondering if they would fit a NB 964. I found out that they won't. They are 10x18 ET40 in the rear. The guys on the 964 turbo board use them for their cars but it appears they are a too tight fit for the regular 964 coupe.
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Old 11-13-2007, 06:06 PM
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I am using Fikse's for the track 18 x 8 ET 51 front and 18 x 9.5 ET 44 rear with 225/265 tires. Works nicely.
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