WaltB

Can anyone confirm that the following will fit on my 2012 997 Turbo S?

Fronts
"9JX19 H2 ET47" 245/35 19"

Rears
"12JX19 H2 ET48" 325/30 19"

They came off of a GT2-RS

I have been getting conflicting information so please only reply only IF you are absolutely sure, one way or the other.


Thanks,

Walt

TT Surgeon

There was a guy on 6 speed that did this last year, not sure what he had to dom if anything, try a search over there too.

WaltB

I did. Came up blank.

Thanks,

Walt

Dallas911Guy

I have GT2 RS wheels and Trefeo 245 and 325 tires on my 2011 Turbo S.

Hold on! Corners at 90 mph.

TT Surgeon

^^I love your signature; "life's too short to drive a ****box"

jhbrennan

Wish I could respond with more knowledge. GT2 is RWD so less sensitive to tire size differences...just make sure you're not doing anything that might cause AWD differential problems on the TT. Looks like a guy in your neighborhood has done this - maybe you can guys can make direct contact.

eurotom

Yes they will work and will fill the fenders out nicely.

Do a search for DaBrat on 6speed. The aspect ratios noted are within Porsche awd
Guidelines you will not chew up your diff.

WaltB

Thanks, will look him up.

Walt

eurotom

Responded with the link on your 6speed thread

Igooz

I just looked at my 997TT and I have F:235/35X19 = 25.48" and R: 305/30X19 = 26.2" and a difference of 2.85%.

On the GT2RS it works out like this F:245X35X19 = 25.75" and R:325/30X19 = 26.68" and a difference of 3.59%

Formula: Wheel Size + (Tire width/25.4)*(2*Aspect Ratio/100) = diameter in inches

The rule of thumb for AWD systems has been for the tire diameter (F vs. R) to be within +/-3% of each other at most. Clearly the less the difference the better. (In the early 90's older AWD systems it needed to be within +/- 1.5% due to the way F/R torque was split with clutches, etc.)

I am not sure what the Porsche recommendation is, but the 3.59% is more than my comfort zone.

WaltB, By the way, the GT2RS has the front fender flare and perhaps (?) more offset on the front wheel for more tracking, where as the TT do not have that. So you just have to check for fender interference. I would be interested in what you find out since I am contemplating changing wheels on my TT or at least add spacers in the back?...

mdrums

Walt, the rears will fit no issue but the et47 9X19 fronts will have too much offset unless you are running at least -2.5 camber up front. I know this because I use the same size offset on my GTS which is a widebody like your Turbo and we both have the same front uprights which effect offset. What you really need up front for a 9" wide wheel is an offset of et50...or 53 at the least. That is a perfect fit. GT based cars use a different front upright so a et47 on a 9" wide whell fits GT3 based cars perfectly

hope this helps

WaltB

Thanks guys for all the responses however the issue has become more confusing and less clear.

I have had two guys tell me they run the exact setup on their Turbo and Turbo S and have done so for quite a while with no issues what so ever. I have had the two local Porsche dealers tell me there would be no problem running with them. I know two Porsche Techs personally that have said they were fine and they they have customers with the same setup that they installed.

Then I have had some folks tell me the tire diameter was just a little outside the limit and would recommend against using them and others that have told me I will have clearance issues.

Very confusing for something that should be black and white.

I guess what I do is install them and report back here with my findings.

Walt

aa909

agree with this. I'm running 19x8.5 ET45 up front and the wheels are perfectly flush with the fender. I think 19x9 ET47 would be another 4-5mm beyond the edge of the fender. Don't know if this would cause drivability issues but it might look odd without the aggressive camber mentioned above

WaltB

Igooz,

I went to tire rack to see what the diameters were for the OE Tires that come on the Turbo S. Three manufactures were listed and all had the same wheel diameters:

F:235/35X19 = 25.50" and R: 305/30X19 = 26.3" with a difference between them of :3.13%

I then looked at the GT2RS with Pilot Cup Sport wheels:

F:245/35X19 = 25.80" and R: 325/30X19 = 26.7" with a difference between them of :3.48%

So the OEM stock tires that come with the car are already slightly over the 3% at the most you stated, if I am doing the math correctly.

If 3.13% is where Porsche starts with on their OEM tires is 3.48 % in an acceptable region?

This is no doubt a question that should be posed directly to Porsche. I fired off an email to them. Hopefully they will respond.

Walt

WaltB

Mdrums,

Is -2.5 camber considered aggressive or just little more than is stock?
What kind of tire wear could I expect with -2.5?

Thanks, Walt