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OK, this has probably been discussed before and anyone is welcome to direct me to the appropriate thread: my 83SC coupe has 6 and 7x16 Fuchs. The rears are - for me - too far inset from the fender whells especially compared to the fronts. I'd like to get a pair of H&R DRM wheel spacers from Performance, but which thickness?? 21-28-32mm (and thicker) are available. Has anyone with an SC and 7" Fuchs done this already. I don't want to spend the (BIG) bucks for a spacer set that's either too thin and doesn't fill the wheel well or too thick and doesn't fit. I've got Bilstein sports so rebound isn't a problem.
Experiential knowledge rather than conjecture would help and, yes, I know these cars are all built differently.
TIA
john

Bill Verburg

You might want to look here for some info

SC/Carrera Wheel Fitments

Chuck Harmon

I had the 1/4 inch spacers on my 83SC.... I should have went with the 1/2 spacers. I had 16" Fuchs
and Bilstien sports and lowered.

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Thanks - I was looking for a way to come up with some sort of 'measurement' procedure to fugure out the spacers. I'm reckoning I'll have to make something up and put the wheels back on with just a few threads (and not drive it) just to see what's what. Since H&R DRMs come in 21-28-32mm for the thinnest ones, I'll start with a 21mm thick something.
Thanks again
john

chrisp

Maybe I can shed some light. If your main concern is filling the fenders then you need to calculate frontspacing (as opposed to backspacing). So I will talk in terms of that.

Most of this can be pulled or calculated based on Bill's spreadsheet. My numbers are slightly different than his because I assume a 7" wheel is 7" wide and so on. Bill seems to have some actuals that refute dimension published by Porsche.

Your stock 7" Fuchs has an offset of 23.3 which gives them a backspace of 112mm and frontspace of 66mm.

9" Fuchs gives a very full fender. They have an offset of 15mm which gives them a frontspacing of 99mm. A 33mm spacer should mimic the fill of a 9".

I have 17x9" Fikse's on the back of my car (8" front) and they have an offset of almost 19mm and a frontspace of 96mm. It looks good with a 255/40-17 on there. A 30mm spacer mimics this.

The 8" Fuchs (which a lot of guys like) has an offset of 10.6mm and thus a frontspacing of 91mm. A 25mm spacer will mimic this.

For the front, a 6" Fuch needs a 25mm spacer to mimic and fill the well like a 7" Fuch does.

If you are not putting a spacer in the front then I wouldn't space out the rear too much so it doesn't look to extreme.

I say put spacers front (25mm) and rear (25 to 33mm).

Maybe Bill V. can read all of this and see if he agrees.

Bill Verburg

That is the root of a lot of confusion. A nominal 7" wheel is not 7" face to face but rather 7" bead to bead(look at the wheel cross section on my wheel page). For Fuchs there is an additional amount of ~.5" that needs to be added to the nominal width for actual face to face dimensions. This flange thickness also varies by wheel manufacturer.

For the purposes of spacer selection the flange width can be ignored as it will be roughly the same for all wheels.

only simple arithmetic is needed to figure spacer width

For ex. if you like the look of a +15mm 9"(bead to bead) rim. Ignoring flange width, because the flange on a 7"(bead to bead) wheel is the same as the 9"
9 * 25.4 = 228.6mm bead to bead width

228.6/2 =114.3mm center line to either edge

114.3 - 15 = 99.3mm distance from the hub mounting face to the outer bead edge.

To replicate this w/ a +23.3mm 7" wheel

7 * 25.4 = 177.8

177.8/2 = 88.9

88.9 -23.3 = 65.6

So 99.3 - 65.6 = 33.7mm spacer width(~1.327")

There are shorter methods of claculating this but i kept it as concrete as possible.

chrisp

Thanks Bill. I did rule out the bead wall as a constant. True there are subtle differences but I think for this, as you've assumed, we can assume it's constant and throw it out.

You and I both came up with a 33mm spacer for a 7" to mimic a 9" so that was the expert second opinion I was looking for. Thanks.

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YES! Thanks
FWIW, the 6x16 Fuchs with 205/55ZR16 Fuldas fill the front wheel well nicely. It's the rears - 7x16 Fuchs with 225/50ZRs - just looks to be an inch too far inset, and a bit goofy IMHO. This info is exactly what I need as I used a shallow water depth finder and got about an inch (25,4mm) of extra space. H&R only makes 21mm and 28mm spacers but I may have located a source for 1inch hub-centrics. If anyone is interested I'll make a follow-on post (with pix).
Thanks, again
john

unimog

If you are looking for Factory Porsche spacers (21mm), I have some on eBay right now.
http://cgi.ebay.com/ebaymotors/ws/eB...tem=7917315412

I don't think there are any 'factory' 25mm spacers, but the 4mm difference is just over 1/10th of an inch.

Don't forget longer studs if you go this route. The 72mm ones are $50 over at Pelican. And if you stay at that length, you can change the rear studs on the axle, without pulling them. Longer (100mm) studs, will require pulling the axles to install them.

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Hi, uni
Thanks. Now I'll have to figure the $$ in simple spacers + studs vs H&Rs. I appreciate everyone's input.
john