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-   -   Frankenstein wheel setup idea —*GT3 RS fronts and GT3 rears on a 991 Turbo S (https://www.6speedonline.com/forums/991-turbo/393404-frankenstein-wheel-setup-idea-gt3-rs-fronts-gt3-rears-991-turbo-s.html)

francisluu 07-09-2016 03:56 PM

Frankenstein wheel setup idea —*GT3 RS fronts and GT3 rears on a 991 Turbo S
 
Bear with me on this —needing help from the wheel and offset experts here.

Before making the jump to a set of aftermarket wheels, I'd like to get a sense of centerlock wheels from the GT cars would fit onto my 991 Turbo S.

According to some of the research I've done so far, the rears of the GT3 will sit ~15mm (.6in) outward than the stock wheels on a Turbo S and sit ~3mm further away from the suspension strut. It seems like there's quite a bit of protrusion outwards but it looks like other aftermarket wheels run aggressive offsets similar to this in the rear and lowering the car will bring it pretty close to a flush stance. --> Assuming this isn't an issue with flinging debris up onto the rear body panels, thoughts on this interfering with clearance WRT the rear steering?

The fronts are where it gets a bit tricky —*standard GT3 wheels will sit 4mm closer to the suspension strut *and* 4mm inboard the wheel well. No chance of a flush stance here because of no wheel spacers on centerlocks. Well, what about the GT3 RS front wheel, which will sit 5mm closer to the strut and extend 7mm outwards compared to the stock Turbo wheels? Again, what do people think of clearance issues here with the steering?


To summarize: would there be any clearance issues with fitting:

- a rear GT3 wheel that extends 15mm towards the outside of the wheel well compared to a stock TTS wheel while being 3mm further from the suspension strut.
- a front GT3 RS wheel that extends 7mm towards the outside of the wheel well but sits 5mm closer to the suspension strut

-----------

Here are the specific measurements I've dug up:

Turbo S Wheels
9” x 20” ET 51 245/35
11.5” x 20” ET 56 305/30

GT3 RS Wheels
9.5” x 20” ET 50 265/35
12.5” x 21” ET 48 325/30

GT3 Wheels
9” x 20” ET 55 245/35
12” x 20” ET 47 305/30

Karl911 07-09-2016 04:38 PM

Why are you making life so compilcated, I have been running 265/35/20Fr and 325/30/ 20 rear MSC2s on stock TTS wheels for over a year.

francisluu 07-09-2016 04:47 PM


Originally Posted by Karl911 (Post 4536916)
Why are you making life so compilcated, I have been running 265/35/20Fr and 325/30/ 20 rear MSC2s on stock TTS wheels for over a year.

I think that's a great tire setup! This thread is more about fitting the wheels themselves and understanding if there are issues with clearances because of the different offsets. A lot of aftermarket staggers and offsets are similarly aggressive so that's what is leading me to consider this route. I have a soft spot for the GT3 and GT3 RS wheels and would love to fit them to the car.

francisluu 07-09-2016 04:49 PM

Actually since we're briefly talking about the larger tire sizes, did it fill up the wheel well a bit more? I suspect it would.

Karl911 07-09-2016 05:02 PM

1 Attachment(s)
I have no issues. Also the rear on the 991.2. TTS are now 12"
I am also lowered

BLOWN SRT 07-13-2016 07:06 PM

I'm running 13" wide rear wheels with 335/30/20 and 265/35/20 fronts on 10.5" with aggressive offsets and am lowered 30 mm all around, with no rubbing. I'm flush with the tops of the fenders.


https://cimg5.ibsrv.net/gimg/www.6sp...f6942b8038.jpg

francisluu 07-13-2016 09:44 PM


Originally Posted by BLOWN SRT (Post 4538402)
I'm running 13" wide rear wheels with 335/30/20 and 265/35/20 fronts on 10.5" with aggressive offsets and am lowered 30 mm all around, with no rubbing. I'm flush with the tops of the fenders.

So good! Do you know what the exact offset measurements are for your rims?

BLOWN SRT 07-14-2016 04:10 AM

Sorry, no idea...but you could call the guys at Wheels Boutique and they can help you with this. They have sold tons to 911 owners and have a very in-depth knowledge of this.

skilly2000 03-09-2019 11:30 PM

did anyone ever try to put the GT3RS wheel on a turbo S and check fitment? I think the issue is strut clearance but it would be great to hear it works.

skilly2000 03-11-2019 08:46 AM

I made a little chart over the weekend to give comparison. The only real solution for TTS cars is the GT3RS option. But keep in mind that the tires spec'd for that car wont work - they are too big and would throw speedometer readings off; not to mention you would very likely have rubbing issues. The clearance is VERY tight with the new width of the wheels. You would need 255/35 R20 for Front and 325/25 ZR 21 Rear. Michelin and Pirelli make compatible tires but thats it. Here is the comparison chart :

note if the measurement was <.5mm I rounded down and >.5mm I rounded up
https://cimg6.ibsrv.net/gimg/www.6sp...0cef17d08f.png

skilly2000 03-20-2019 10:14 PM

I (kind of) stand corrected. Where I thought that the GT3 wheels wouldnt look right because of the additional positive offset with the fronts, it actually looks like they were made for the car. Clearance isnt a problem for the rears either, and my car is lowered 1" as well. I really like the set up! One more thing - I can confirm that the 4mm offset difference in the front leaves just a couple of mm of space between the wheel and the strut. Im not convinced that the GT3RS wheels would work, even with a corrected tire size.

Note the GT3RS side skirts - its a 15min swap out with the OEM part easy to get from Suncoast.

https://cimg4.ibsrv.net/gimg/www.6sp...2f183c9c8c.png
https://cimg9.ibsrv.net/gimg/www.6sp...d275f35b47.png
https://cimg2.ibsrv.net/gimg/www.6sp...4e1a6687c6.png

991ttpines 03-21-2019 09:52 AM


Originally Posted by skilly2000 (Post 4772628)
I (kind of) stand corrected. Where I thought that the GT3 wheels wouldnt look right because of the additional positive offset with the fronts, it actually looks like they were made for the car. Clearance isnt a problem for the rears either, and my car is lowered 1" as well. I really like the set up! One more thing - I can confirm that the 4mm offset difference in the front leaves just a couple of mm of space between the wheel and the strut. Im not convinced that the GT3RS wheels would work, even with a corrected tire size.

Note the GT3RS side skirts - its a 15min swap out with the OEM part easy to get from Suncoast.

https://cimg4.ibsrv.net/gimg/www.6sp...2f183c9c8c.png
https://cimg9.ibsrv.net/gimg/www.6sp...d275f35b47.png
https://cimg2.ibsrv.net/gimg/www.6sp...4e1a6687c6.png

Looks great!! Are the fronts tucked in like oem turbo s wheels?

Just to be clear you went with a full gt3 wheel set up? Fronts and rears?

Also do you have the part number for the side shirts?
Can't seem to find them on Suncoast website

Great job!
​​​​

skilly2000 03-21-2019 10:21 AM


Originally Posted by 991ttpines (Post 4772686)
Looks great!! Are the fronts tucked in like oem turbo s wheels?

Just to be clear you went with a full gt3 wheel set up? Fronts and rears?

Also do you have the part number for the side shirts?
Can't seem to find them on Suncoast website

Great job!
​​​​

Thanks - its the full GT3 wheel set up, which I had refinished in gloss black. With the ceramic brakes, we don't have dust issues. The rears are flush to the fender (with zero rubbing) and the fronts sit pretty close to the same as OEM TTS (they sit 1/8" more inward) - side view attached so you can decide for yourself if its tolerable...for me it works!

As for the RS OEM part numbers, they are:

The OEM part numbers are:

991 504 595 86 0K1
991 504 596 86 0K1

Suncoast is the place to get em though:
https://www.suncoastparts.com/product/PK991TSKIRTS.html

https://cimg3.ibsrv.net/gimg/www.6sp...3d207a7af.jpeg

Gixxerboy63 10-11-2019 09:15 AM

Bottom line is that GT3 RS wheels will work nicely on lowered 911 Turbo S.

Yes, they will be aggressive, but they won't poke past the fenders.

Reference info;
Turbo front: 9x20 ET51
Turbo rear: 11.5x20 ET56

GT3 Front: 9x20 ET55
GT3 Rear: 12x20 ET47

GT3 RS front: 9.5x20 ET50
GT3 RS rear 12x21 ET48

GT3 RS 20/21 setup for Turbo S.
There are two recommended front tire sizes to stay within the delta of the AWD system (so that you do not destroy your transfer case)

front: 255/35/20 or 265/30/20
Rear: 325/25/21

I am running a similar 21' setup on my Turbo S:,
Signature SV303S with Centerlock option (First official set made!) 2 piece construction: Finish is Polished lips, Brushed faces and Gloss black barrels with hidden hardware.

21x9.5 ET45 255/30/21 (5mm closer to fender than GT3 RS)
21x12.5 ET48 325/25/21 (exact spec for GT3 RS)
no rubbing whatsoever!


Enjoy!

r11rs 10-11-2019 10:43 AM

Thanks for this. Looks nice! Wondering what the cost on those was ballpark? NVM looks like $6k+.


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