Is my calculation correct (offset)?

[Arnoud911Targa]

Is my calculation correct and will these wheels work for a 911 wide body SC?

I have a set of 944 turbo Fuchs:
7Jx16 ET 23.3
8Jx16 ET 23.3

I would like to run the 8J in the front. I think this will work with a spacer to put it more outwards.

And I would like to widen the 7J to 10J. If they only widen it at the outer half the ET value will be:
7J x 25.4 (inch to mm conversion)/2 = 88,9 (middle of the wheel) adding the 23.3 offset = 112.2 backspacing

Adding 3” makes 10J x 25.4 (inch to mm conversion)/2 = 127 (middle of the wheel)
Backspacing of the 7J was 112.2
ET of widened wheel will be 112.2 – 127 = -14.8

To me it looks like 10Jx16 with ET of -14.8 will work for my wide body sc. I think have like 15mm left for a spacer to play with. Am I right?

Right now I have 10Jx17 ET14 with 43 spacer so to get the new wheels in the same spot I need to add a spacer of ET-14.8 - ET14 = -28.8 mm to the outside
Loosing the spacer will make 43 -28.8 = 14.2 to the inside comparing with my current setup.

[Bill Verburg]

Originally Posted by Arnoud911Targa

Is my calculation correct and will these wheels work for a 911 wide body SC?

I have a set of 944 turbo Fuchs:
7Jx16 ET 23.3
8Jx16 ET 23.3

I would like to run the 8J in the front. I think this will work with a spacer to put it more outwards.

And I would like to widen the 7J to 10J. If they only widen it at the outer half the ET value will be:
7J x 25.4 (inch to mm conversion)/2 = 88,9 (middle of the wheel) adding the 23.3 offset = 112.2 backspacing

Adding 3” makes 10J x 25.4 (inch to mm conversion)/2 = 127 (middle of the wheel)
Backspacing of the 7J was 112.2
ET of widened wheel will be 112.2 – 127 = -14.8

To me it looks like 10Jx16 with ET of -14.8 will work for my wide body sc. I think have like 15mm left for a spacer to play with. Am I right?

Right now I have 10Jx17 ET14 with 43 spacer so to get the new wheels in the same spot I need to add a spacer of ET-14.8 - ET14 = -28.8 mm to the outside
Loosing the spacer will make 43 -28.8 = 14.2 to the inside comparing with my current setup.

Fuchs 7ET23.3 has a backspace of ~120mm/4.7" overall width of 193.675mm/7.625"

when you do these calculations you need to use the overall width as shown above.

10ET14 w/ 43mm spacer is 10ET-29

add 3" to the frontspace of a Fuchs 7ET23.3 gives an overall width of 10.625"/269.875mm if you don't change the flanges. backspace stays ~120mm and ET is -14.8

[Arnoud911Targa]

Thanks Bill,

I did make some detours in my calculation but luckily we came up with the same values. :-)

So I guess it will be fine to add 3" only on the outer-halve?

Thanks,