V

hi guys!

Did a bit of research and I still have a few questions unanswered. I am contemplating building a set of GT2 wheels using the 993 RS speedlines as a base for this. What I need to know is:

1. Can someone confirm these specs of the 993 GT2 Wheels:

Front: 9x18 ET34
Rear: 11x18 ET18

2. More importantly: How deep are the front and rear outer rim halves?

My guess: Front: around 2,5" outers Rear: around 4" outers

3. For those of you who have the 993 RS speedlines, is figure "C" in the diagram below different when you compare the front wheel centre and the rear wheel centre? E.g Are the centers identical as far as caliper clearance or do any of the centres allow for more caliper clearance than the other? According to my calculations (taking total wheel width and ET into consideration) it seems from a theoretical viewpoint that the front wheelcentre would have a bit less caliper clearance than the rear wheel centre. I might be mistaken though..

Hopefully with some help I will be able to do this. If someone on here have OEM GT2 wheels that that would be perfect. Graemem where are you??

Thanks guys.

Felix

Try asking on the 993 turbo forum; you'll probably have better luck...

V

Thanks phelix, will do.. But guys come on, this is a 993 forum right?? Anyone?

Bill Verburg

The GT2 Evo's used
10x18 ET 32 or BBS rim AV ET32
&
11x18 ET 14 or BBS rim HA ET14

tires were
245/645 x18
&
305/675 x18

V

Thanks Bill.

So for example Graeme's car has 10x18 ET32 up front?

Bill, could you address question 3, having just bought the 993 RS speedlines?

Is figure "C" the same for rear and fronts wheelcentres? If you have the big reds,
I assume you need more caliper clearance up front than in the rear? How's the caliper
clearance front/rear now that you have the 993 RS speedlines mounted?



TIA

Bill Verburg

the centers appear to be the same on all of the 3 piece wheels that i have.

Jean

Viggo

The sizes posted by Bill are the correct ones for the race car as TB mentioned on the other board. They will need aggressive flares on your car.

I don't have my wheels anymore, the centers are magnesium unlike the RS Speedline wheels. One person that could help you out is "Porschemeister" , he has the wheels and can maybe measure them for you.

In case it helps, here is a picture I found of my car when I had the Speedlines fitted, you can maybe see the depth of the lip between front and rear.. These are the GT2 street sizes, with offsets per your first post. I have a shim in the rear here.

V

So figure "C" in the diagram are the same for the fronts and rears?

If yes, how come the offsets are different? Here is my reasoning:

fronts: Inner hoop 6,5" + crush ring 0,25" + outer hoop 1,25" = 8x18 ET52
rears: Inner hoop 8,5" + crush ring 0,25" + outer hoop 1,25" = 10x18 ET64


To make the offsets comparabe (and thereby figure "C" comparable) let's
resize a front wheel to make it a rear wheel:

Front wheel replace the inner 6,5" hoop with an inner hoop of 8,5". Hereby, we are
increasing the total rim width with 2" from 8 to 10". However, the offset will not change
from 52 to 64 but rather from 52 to 77. (ET52 + (25+25/2)) = 77. Am I missing something
here? Are my calculations faulty? It would make more sense if I divided by 4, but I don't
think it's how you calculate it. Then it would make sense: (Going from 8x18 to 10x18):

ET52 + (25+25)/4 = ET64,5
to 52

Bill Verburg

If the outer hoop on oem Speedlines is the same on 8" & 10" then the centers are different. But I don't believe that to be the case(but I've been wrong before too)

I just measured the distance from the outer edge plane to a bolt head.

the 10 is ~1/8" deeper.

I also measured my spare Speedline Alisssios which are unmounted and easy to see see whats what

they use
9 > 2" outer & 8" inner = total width 10" (ET 50)
10 > 2.5" outer & 8.5" inner = total width 11" (ET56)

the seal doesn't add to the width

Bill Verburg

Jean, how about some more pics of your car?

Jean

Bill I have some old ones handy

V

Spot on Bill . Jim Dorociak just confirmed this, the rear wheelcentre is ~1/8" deeper, just as you said.

I'm 99% sure all four rimhalves are 1.25" on the 993 RS Speedlines, as opposed to on the 3.6 Speedlines where the fronts are 1.25" and the rears are 1.75".


Now, what bothers me though is why would the rear wheelcentre allow for more caliper clearance when it is in the front that it is needed the most, correct? I mean the big reds up front demand more caliper clearance than in the back..

Bill, do you think one of your front wheels would clear the caliper if mounted in the back? I don't see why it shouldn't but just wanted to make sure if it's possible to swap the centers without issues and start to build from there with inner/outer rimhalves. Thanks again.

Oh and Jean, your car is SICK

Bill Verburg

I'll be putting my track wheels on next week and check.

As far as brakes go the 993RS front and rear calipers are the same width and need the same clearance.

mine have ~ 1/4" clearance in front and ~3/4" clearance in back


Thanks Jean, your car looks great!