PTurbo

Hi there. I live in France and own a 996 Turbo and I love the GT2 wheels with the wider tyres. Question: is it possible to mount these wheels incl. tyres on the 996 Turbo ? Is there a retrofit wheel set available from Porsche ? Is it officially approved by Porsche to mount the GT2 wheels on the 996 Turbo ? If not, any reason why there could be problems with the GT2 wheels on the 996 Turbo ? Please help. Different sources tell me completely different things and I am very confused. Any hint what kind of tyre pressure to use on a 996 Turbo equipped with GT2 wheels/tyres ? Somebody on another forum told me that I have to have the steering angle sensor recalibrated if I go for the GT2 wheels/tyres on the 996 Turbo. How can I recalibrate it and is it really necessary ? Another question: what advantages/disadvantages does a one mass flywheel have on a 996 Turbo ? What about a stronger clutch disc (not Sinter but organic) ? Recommended or not ? I heard about a retrofit gearbox cooler, what is that good for ? Does it make sense on a 500 HP Turbo ? Sorry for the many questions but I am a Novice to all this stuff and you guys seem pretty knowledgable. Thank you.

Flat6

Unless you go two wheel drive, then the GT2 rims will not work on your Turbo.

Because the Turbo is AWD, there can only be a 1% size difference between the diameters of the front and rear tires. The GT2 with its wider tires and different sized sidewalls will change this ratio (It's to bad, 12 inchs of rubber on the rear would be pretty cool).

Flat6

ag

Flat6-
Its been quite awhile since I ran the numbers but I am pretty sure they are well within the limits of the visco mechanism. Although its been awhile, I was comfortable enough with the numbers that I bought the GT2 wheelset and am awaiting the 996TT with powerkit onto which they will be mounted.

PTurbo

Thank you for trying to help. But you will be suprised to hear that they actually do fit the 996 Turbo. Yesterday evening, I met a tech from Porsche France at my dealer. We discussed the GT2 wheel issue and he told me that there is no problem with the GT2 wheels on the 996 Turbo but Porsche does not approve mounting them. However he told me that there is no technical reason not to mount the GT2 wheels on the Turbo. So I took the risk and I had them installed today and there does not seem to be any problems so far. The ESP/ABS works just fine, the tyres do not touch the springs or any body part and I already had a H&R coilover kit installed before. I drove the car today for about two hours from Nice to St. Raphael/Frejus and back on a quite challenging seaside road. Only some minor work on the wheel housing was needed. The tyres are Michelin Pilot Sport N0. I have to confess however that the drive feel has changed a bit, steering feels more tight, but suprisingly, the mild understeer from the OEM tyres seems to be reduced.

Oak

cjv, I have just installed 19" HRE 540's 8.5" front and 11.5" rear with the new reversed drop centers. I waited 6 weeks for custom offsets, but well worth it. These wheels are gorgeous! I went with 235/35/19 front and 315/25/19 rear and have no problems ABS/PSM. I would love to see some images of your Kinesis wheels!

Flat6

Guys... no offense, but there is a reason Porsche is picky about rims and tire diameters and it has to do with the viscous coupler...

under normal driving the front tires get a 5% load... when slip occurs the speed ratio between the front and rear changes and causes friction in the viscous coupler. This friction causes "goo" in between two clutch plates to swell and engage.

Running tires that are out of ratio will force your coupler to always read a difference in speed, and will always cause unneeded friction... which will eventually lead to failure of the coupler... and in the least event lots of unneeded heat (friction) in the coupler unit.

Thats how my mechanic explained it to me... everything else I've read seems to point to the same concept...

It will work, but not as intended, and probably not indefinitely.

Flat6

PTurbo

Maybe I am not supposed to say that but the tech told me that the only reason Porsche does not offer the GT2 wheels for the 996 Turbo is marketing. Same reason why Porsche does not offer the GT2 front nose and rear wing on the Turbo and same reason why the X50 Turbo does have a lower power output on the paper. I heard about the viscous coupler problem too but the tech told me that this is one of the official statements for customers who inquire about the GT2 wheels. Another funny thing he told me: the 996 Turbo and the GT2 have the same European Community vehicle approval registration number which officially makes out of the 996 Turbo and the GT2 practically the same car. Theoretically speaking.

PTurbo

I will do that as soon as possible. Maybe I have the chance to do what you proposed on a nearby car driving safety training area. But I do not think I find out something different because the seaside road I drove on is full of bumps and other nasty obstacles, one reason why lots of mules of different car makers are using this road for testing. Oh I forgot, my dealer told me that they also had to cut out a piece of plastic in the wheel housing (?) as far as I remember. The only problem we have now is the correct tyre pressure. The tech already left my dealer and we do not know whether to use the OEM Turbo or OEM GT2 tyre pressure. My dealer will talk to him next week but right now I am using the Turbo tyre pressure to be on the safe side.
I read that you installed a one mass flywheel on your Turbo. Do you need a stronger pressure plate too or did you use the OEM Turbo one ? We also want to install a thicker swaybar in the rear to eliminate understeer completely.

VS

PTurbo,

since you have already installed H&R coilovers, you can use GT2/GT3 adjustible anti-roll bars rear and front.
This way, you will have more options for the street/track setup.

PTurbo

Thanks, yes it is possible. But my dealer thinks that too many options are resulting in way too much confusion about the setup. A slightly thicker swaybar in the rear will reduce the understeer and I am not a professional race track driver, so this setup will be just fine for me. I love the setup of the H&R coilover kit, it is perfect for street driving and even some track driving. On the race track however, a more professional setup is needed. And do not get me wrong: the OEM suspension of the Turbo is perfect and Porsche did a good job. But I wanted my car to be lower and I did not want to go for lowering springs because my dealer had a very bad experience history with them.