17" Fuchs Backspacing????

[a_bayuga]

I'm sending a set of front 16x6 and rear 16 x7 inch fuchs wheels to Tru Design but need to tell Jim what back spacing to build the wheels which are going to be 17x9 and 17x11?

The car is a 1986 3.2 Carrera with added 9" front and 11' rear steel flares with original rear torsion tube (not 930).

What is the ideal backspacing I should tell him such that I do not need spacers?

I have the whole suspension off the car so I cannot measure at this time.

Thanks

[Joe Bob]

I would assume the same as your previous 7 and 8 inch Fuchs....since you have added 2 inches on the fenders, right?

[Joe Bob]

[Joe Bob]

[retrotech]

Are the Tru Design wheels safe for track use?
Do they weigh more than Fuchs same size?
What do they charge to do a wheel?
Sorry to hi jack, but it sounds like you will have answers to these questions.

Stephen

[911-32]

Originally Posted by Joe Bob

I would assume the same as your previous 7 and 8 inch Fuchs....since you have added 2 inches on the fenders, right?

That would be right if he was doing 9s and 10s as he has added 2 inches of extra flare at each corner and would be adding 2 inches of extra track at each corner. Given he wants 11s in the rear he needs 1 inch more backspace than his 8s. Depending on cambers, tyres etc there is a lot more possible finessing than this.

Of course, I am pretty sure that searching will find more precise measurements than these

[JeremyD]

My wheels offsets are:
9 x 17 ET 17
9 x 11 ET -8
Tires on the picture are Nitto NT05 - 255/40/17 in the front 315/30/17 in the rear - but really Jeff Alton is the guy to talk to about wheels and offsets. I probably have room for a 9 x 17 with a 10 or 11 offset in the front -

Here are my zuffenhaus fuchs (same offset)


and my true design wheels



My car has a stock suspension (SC/Carrera) no spacers

[retrotech]

Any comments or advise about Zuffenhaus versus TruDesign?

[Canada Kev]

Zuff are new, TrueDesign are made from original Fuchs.


Jeremy, I think your numbers are a teensy bit off...

Originally Posted by JeremyD

My wheels offsets are:
9 x 17 ET 17
9 x 11 ET -8

[JeremyD]

woops

9x17 ET17
11x17 ET-8

[KTL]

Rears are 17x11. Jeremy's wheels were built with 951 Fuchs centers which have the added hub depth for brake clearance. That effects the offset a little bit because these centers have more "meat" in the hub than do the regular 16x6 or 16x7 centers.

TruDesign are built from used wheels, which is somewhat of a risk because your wheels could be quite old- 16 in. Fuchs date back to the mid-late 70's. That being said, people have been making custom Fuchs out of the used centers for a very long time and it's proven to be great. You'll get them made the way you want and have a set of wheels to use in a timely fashion. Zuff wheels have been great wheels, but take quite a while to get and you'll pay over twice the price

[a_bayuga]

Thanks guys for all the replies.

This 17 x 9 wheel I have to try out has the following parameters:
Overall Width 10"
Back Spacing 5.75"
ET I calculated as 19 (maybe wrong)

I used:
Overall Width = 10"
Center Line as 10 / 2 = 5"
(Backspacing - Centerline) = 5.75 - 5 = .75 "
ET = .75" x 25.4mm = 19

I placed the rim in the rear with a 2" spacer to see how close it would be to the edge.
Note: I have no idea what the camber is set to or the ride height. I just wanted to see.

Here is the result:


















Pretty Big A$$ spacer:




So by adding the two inches and going to a 11" wheel, which I guess is an overall width of 12", my ET should be set around -6.35 for the new TruDesign wheel (without spacers)???.

Centerline = 6"
Backspacing 5.75"
(5.75" - 6") = -0.25"
ET = -0.25 x 25.4 = -6.35

Is this correct or are my calcs or concept of this whole backspacing FUCH'd?

[brentrussell]

I think you're very close, I'm actually measuring mine tonight as the centres will go into the hoops this week.
One thing to consider, I noticed you have no Brake disc on rear.... this will add approx 5mm, not a major but will push the wheel out 5mm when added.
I'm using 17x9.5 and 17x11 so my Front offset won't be right for you but you could use my Front space measurement as a quide.

Kevin above is not rarely correct re the 951 centre, it does not matter what your center is for offset or backspace, however it will effect your caliper clearance or X-factor when wanting brake clearance.

I am using 16x6 and 16x7 centers, a 28mm spacer on front so I can clear my 996tt brakes, not ideal but the brakes will look cool

My initial measurements were 17x9.5 ET5 but it does not make sense, I have since fitted all suspension and lowered car to desired ride height so as to confirm numbers.

Will report back tonight.

Brent

[a_bayuga]

Originally Posted by brentrussell

One thing to consider, I noticed you have no Brake disc on rear.... this will add approx 5mm, not a major but will push the wheel out 5mm when added.

Brent

Glad you reminded me, I was in a rush to see. Thanks

[brentrussell]

Measured mine tonight and I am going with the following:
Front 17x9.5 +35P
(I am using a 27mm spacer) Plus raising spindle 40mm which will push the wheel in.

Rear 17x11 +0P
I spent quite a bit of time double checking this as I remember reading somewhere with Jeremy's car that his are -8N and are very close to spring plate. My measurement was 170mm to spring plate from bolt face or about 160mm to adjustment bolt if you end up being located there depending on wheel diameter, I will be past there with 17". Based on 17x11 at 0P it will be 152mm inward giving me a clearance of 18mm less Tyre bulge. On the outside I think I may need to trim the guard lip depending on ho much camber I run.

I'm using 255/40R17 Fronts and 315/35R17 Rears, Nitto NT05's

Hope that all helps or add's more confusion?

Brent