993Purple

Hello everyone, newbie here.

I recently purchased a 1995, 993 C2 in Germany with light bodywork damage after the previous owner had a slight run in with a barrier.

I have had it professionally repaired - now i am moving on to the second step of some light mods to fit it to my taste. I am driving around 40k miles a year so safety and performance are my main goals.

To start with, some BG info and disclaimers:

1) there are multiple threads out there discussing tire fitment and choice and i am certain i have by now read most of them. I apologise beforehand if some of my questions do not sound well informed - i d rather sound stupid then assume i know sth and turn out to be wrong.
2) the setup is for street use. Looks are ofc important, so i will forego some ride comfort in that respect - but since i live in Germany, (i have spent 4 years in the US/Canada) i think it is safe to say i the effect on ride comfort wont be drastic.
3) Germany has a TUV as many of you know. That limits my choices for street legal wheels to the extent that i practically have to go OEM or BBS (with few other options). I have basically accepted that i wont be able to get the wheel setup street legal. Therefore the only real limit is that the tires dont stick out over the edge of the bodywork (nonewithstanding that i will only buy quality wheels regardless of missing TUV certification).
4) Therfore I am only considering forged 1pc wheels for performance and quality reasons. Tire of choice is Michelin PS4S.
5) I do not want to use BBS LM. Lets just say they look nice, but its not for me.
6) I drive around 40k Miles / year - 95% street, 5% track.

The Setup:

KWv3 Suspension
HR Stabilizers front and rear
Big Red Brembo upgrade (322mm front/rear)

So here we go: now i have arrived at the usual problem: wheel/tire setup.


A. First Question: I would like to get as much "rubber" on my 993 as possible - mainly for performance and thereby safety reasons. simply physics. no ESC means i need as high of a physical limit as possible in case of an emergency manouvre. I will have to use minimum 18" due to the size of the new breaks. 17" are not an option.

My initial thoughts were 18" 9,5 front / 265 and 18"/19" 10,5 rear - 285/295. Many threads have already pointed out the optimal front width to be 235 on 9" with a max of about 245 before it starts to rub (rub is a no go).
Similarly, rear seems to handle up to 11" with 295/315.

A1. Am i right in assuming that 265 on 9,5" will rub - most tire tables suggest 265 being the optimal width on that wheel size. Likewise, 235 seems small on a 9".
A2. Going for the maximum suggested practial setup - lets say 245/18/30 and 295/18/40 does anyone here have experience with this setup for street in Germany/Europe?
A3. The difference front and rear seems quite large to me - how does this affect driving dynamics? I have driven square and offset of about 20 or 40. but 60 or up to 80 millimeter difference sounds like a lot.

B. Second Question: Effect of ET on wheel choice.

I am currently (and yes i know some will crucify me for this) looking at SSR Tanabe GTF01 as a possible fit for the car. Ignore that they are 114.3x5, due to the fact that there are so few options with 130x5 anyhow, i have come to terms with the fact that i have to run an adapter plate. Since i wont be getting TUV for any of my choices - any wheel design - bar quality concerns, is up for discussion.

B1. The GTF01s are running ET22 - which is a far cry from the required ET50+/-
Now i will "add" ET with the required adapter plates for all intends and purposes acting like spacers. But here the details of the mathematical exercise are starting to elude me. Is it possible to fit these, or should i forget about it completely.
My thinking - if 18x9" ET 50 fit - can i say 18x9" ET22 + 30 spacer fit? I am assuming this is way to basic an assumption.
B2. Furthermore - adding the much larger breaks - how does this affect the calculation? does anyone have experience fitting the big brembo's?

Thank you to everyone taking the time to shed some light on this issue. i know many of you have done so before. I am posting is because of my interest in an odd wheel choice and the bigger breaks necessitating 18" - the combination of which i couldnt find an answer to in the forum.

boomboomthump

Three things...

1) 265 and 9.5" is certainly problematic and will rub. The most common setup is 225/40-18 on an 8.5" wheel, followed by a 235 on an 8.5". A 9" front wheel is also doable but depending on offsets, you will face more rubbing at full clock of the steering (which is also a problem with the aforementioned tire sizes in some scenarios).

2) You have your understandings of offsets mixed up. If the front wheels you are considering are ET20 and you add spacers (to change the lug pattern) that will make the problem worse not better. Spacers reduce the ET number, not increase it. So ET20 would go to ET5 as an example and that wheel would stick out from the fender by a few inches. I believe most bolt pattern conversion spacers are minimally +15MM offset. So you would need that wheel to be ET60 so that after the spacer you're around the typical ET45 area up front. As you can see, you're about 40MM off in your calculation.

3) Are you referring to the factory "big red" brakes (made by Brembo) that came stock on the C4S, Turbo and 993RS? or are you referring to aftermarket Brembo brakes?

993Purple

Hej Boom,

thank you for your input!

1) noted, thank you - i expected as much.
2) ah ok, well that makes a lot more sense. meaning i can forget anything lower then ET50+ or rather 60.
3) I am not 100% sure - i would assume they are the originals - as its a name Porsche aftermarket Supplier and the product is called "Big Reds"

boomboomthump

Post pictures of the brakes.

Also, suggest you thoroughly review THIS THREAD. It has tons of documented wheel sizes, offsets, pictures and tire sizes. Regardless that it is focused exclusively on the Tramont Cup 2 wheel, it's a great resource to formulate a wheel/tire plan no matter what wheel you end up choosing.

993Purple

the breaks:



thanks for the link. i ll have a look.

boomboomthump

OK, factory big reds. I missed in your opening post that the front/rear rotors were both 322MM.

Was concerned you may have been referring to aftermarket Brembo brake upgrade (even larger calipers/rotors and Brembo logo branding).

993Purple

Ah yes, i was considering those at first, but they are without TUV. its one thing to have to change the wheels if they stop you, another to have to change breaks as well.

71-3.0-911

I don't think those are big reds. Red, yes. I always thought the big reds had the 5 holes in a row vs 4 of the regular. See below from RosePassion's website.

993Purple

https://www.fvd.net/de-de/FVD3522946...-scheiben.html

this is where i got them from. FVD Brombacher is pretty much the authority over here for everything aftermarket Porsche. but you might be right.
EDIT:
maybe i just got the wrong picture?

https://www.fvd.net/de-de/FVD3511916...-scheiben.html

Bill Verburg

What fits and what doesn't depends on the suspension setup, ride height and alignment specs as it does on the wheel and tire specs

Here are some pics of my car, very low

The 993 RS wheels are the tried and true TuV approved approach, 8 x18 ET52 225/40 and 10 x18 ET65 265/35



The widest wheels I've been able to fit 8.5 x18 ET54 235/40 or 245/35 10 x18 ET65 275/35 or 285/30


a group shot with the same sized wheels


There are some real advantages to shorter tires
best
245/35 & 285/30
next best 225/40 & 265/35
tallest I'd want to use 235/40 & 275/35

Here's a comparison of 993RS spec to max fit at that ride height, among the advantages of the shorter tires is a net gain of ~14lb-ft freed up for acceleration

pp000830

Hi 993Purple,
I see some logical disconnects in your posting:
"The setup is for street use." "I drive around 40k Miles / year - 95% street, 5% track"

"I will have to use minimum 18" due to the size of the new breaks. 17" are not an option." "i will forego some ride comfort"

To be clear 18" wheels will result in a harsh ride also since the tires will be very low profile there will be no warning when they are at the edge of their grip. They will simply let go and slide, not exactly a safety-oriented option for a predominantly street-driven car.

Consider keeping the stock brakes that are outstanding, to begin with. For a car being driven 40K miles a year consider stock 17 or even 16" wheels to provide some compliance.

My suggestion is to drive the car for a year or so to get a feel for it before jumping into modifications. Your modification desires will most likely evolve.
Andy

boomboomthump

Not sure what "kit" that is from Rose Passion but it doesn't seem to be a picture specific to 993's given the adapters (in blue) for the calipers.


In any case, to answer your question, the pic the OP posted is rear brakes, not fronts. The fronts have rows of 5 & 4 holes and the rears have rows of 4 & 3. Even though the OD is the same (322MM) the surface area is different given the rear hub differences because of the parking brake shoes underneath.

Bill Verburg

Those are 993RS fronts all right, even have the aluminum backplates
Front 993RS 32x322, 36/44 pistons, pads ~75x132mm, generate 2306nm of torque ~70bar line pressure



993RS rear 28x322mm, 30/36mm pistons, pads are ~132x71mm,generate1618NM @70bar line pressure


f/r 993RS calipers


not to be confused w/ 993tt rears, fronts are the same but 993tt rear 28x322mm, 28/28mm pistons, pads are ~132x71mm,generate1155NM @70bar line pressure

These are RS modified to fit the rear of my '76 Carrera 3.0, 30/36 pistons


these are stock 993tt rear 28/28, uses the same pads as 993RS rear or regular 993 front


tt or RS f/r pads, I don't use the spiders( the rear here is RS tt has smaller spring clips) as they don't seem to stop noise and make pad changes a PIA

boomboomthump

Just to be clear, the first pic the OP posted were rears, hence the different drilling pattern on the rotors that @71-3.0-911 called out.

The second pic @993Purple posted were fronts but not factory rotors (they're one piece and vented at the hubs on the front side).

boomboomthump

Bill...

No dust shield/backing plates on yours? I was debating whether to ditch mine or refinish when swapping over to the 993RS calipers/rotors.

Also for some reason I thought you were also in the "no spiders" camp. Was planning not to run them since a decent amount of folks seem to report decent results without them. They seem like they can be just as much of a detriment as an improvement.


EDIT: oops, I see you did say you DONT run spiders (even though pictured). That's what I thought.