Originally Posted by MAKHNO

So heres a follow up to what I ended up doing and why.

I have just returned from a two day closed trackday at the Nürburgring organized by Porsche, where many of the instructors are VLN drivers (like ALMS, DTM, etc. only all sessions are on the nordschleife :-) )

I went to Manthey Porsche who are located just a few minutes from the entry to the ring.
I guess for most of you no explanation of Manthey is necessary, but for those who don't know them, Manthey won 5 of the last six 24H races at the Nürburgring (well counting 2012, 5 out of seven, but this year no GT2 class, so they could not run their GT3 RSR, only the GT3 R). They are also a development partner of Porsche Motorsport and tests most new parts coming out of the motorsports division of Weissach. Manthey ran the GT3 R Hybrid on the ring too.

They recommended the same size wheels as you all did, 9x19 and 12x19.
So I went for the Manthey MM-1 forged rims (8.2KG front and 10.6 KG rear)

For the tires they said 325 rear would rub a little on all NB cars (even 997.2 GT3) so would require light modifications to wheel arches and inner plastic. They would stick with the 305 which I ran with the MPSS, the 305 on a 12" rim would also strecth the tire sides a little compared to a 325.
For the front I ran 245 MPSS and asked for 265, but they would not recommend either, they would use 235 for increased high speed stability. Since I use it as a DD doing 250KM/h cruising on the autobahn in germany with 285 stints here and there high speed stability sounds right.
Also the Nürburgring northern loop is the track with the fastest avg. speed in the world (yes some ovals in the US are a little faster, but, not trying to offend any one, race tracks they are not).

I thought I would get the Trofeo R but I couldn't source them at the ring, but the MPSC are in stock many places. So I got the MPSC+ N1 (Manthey said the N-rated Cup tire is very different from other Cup editions).

To counter udersteer in a 235/305 combo thet slightly increased offset from ET67 to ET68 in the rear but on the front rims they decreased it massively frm ET57 to ET45. Let me tell you, those rims extended so far out of the car while it hung on the lift I thought they were crazy and had to remind them it wasn't a RSR.
But they got two lumps of wood and placed one under the front right and left rear wheel and lovered the lift, to compress the dampers completely and you could just barely get something between the tire and arch, but technically there was air between the two.

For those of you who hve driven the Nürburgring you know the compression at the end of Fuchsrohre and the g-forces in the Caroussel are insame and will make your wheels rub if in any way possible - but they didn't.

The result: :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-)

Understeer gone, planted, imense stability and confidence, increased front rear track diffenrece of 26mm
It's like having a 991 only with mechanical telepathic steering.

Hope this all makes sense.

Thanks for all your help and comments ... now on to all the suspension and aero bits ...


Sincerely,

Michael