Duc Hunter

So I just picked up a sweet Turbo (pics will come soon). It has mismatched brand tires, and the fronts are old (in years) so I want to get some new ones. I have been searching al over this board and learned the basic tenants....being;

• The car tends to push, so wider in back is not good, better to go as wide as you can in front and not so much in back.
• With this AWD system we need to maintain the same diameter front/back. 0 RPM difference to about 5 more RPM (Rear .5% faster than the front stock) in the rear is tolerable based on stock fitments.
• 18" rims are better for track/handling, 19" are more for looks and street use and can ride more harshly
• Rear tire sizes seem to limit our selction for tires more and more, esp in 18
• GT2's run 18x12" rear rims, yet run a 315 tire...even though most 315 tires I see have said their max rim width is 11.5" which is interesting to me
• In developing the 997 Porsche started out using our suspension, and learned that they wanted more headroom terms of strength because the 19" they were using of the 997 put a larger load onto the suspension components.

I may run 19" for the street, esp since it seem I can get a favorite tire of mine (Michelin PSS) in 19"....but in 18" the rears are not available.

What I have not seen is how wide we can go up front...without rolling the fenders? In my mind going as wide as I can up front, and then find a corresponding rear tire that matches the RPM might be an ideal way to find tire sizes. It seems 315 is about as wide as we can go in back, and some tires (offset and rim width dependent) may need our fenders rolled to accommodate them.

Some options, from an RPM standpoint, look like;

• 235/40-18.....315/30-18
• 255/40-18.....295/35-18.....can we run a 255 front?
• 225/35-19.....315/25-19...rear good on 12" rim
• 235/40-19.....305/30-19 Mich PSS available
• 245/35-19.....295/30-19
• 245/40-19.....325/30-19 Mich available, prob too wide in back
• 255/35-19.....295/30-19 Mich PSS Available, Ft may be too wide

So how wide can we go up front and back in an 18" or 19" fitment with the right offset wheel?

How wide can we go in rim width? GT has 8.5/12?

Dock

Are you planning on tracking this car?

jeanmarcboilard

I think you can scratch 315 25 19 off your list. As far as I know they're not available in a quality tire anywhere.

Duc Hunter

I may track it on occasion....1-2 year. If I get into tracking it I will set up some 18"s for track us. I also have a very well sorted 2011 Audi Avant that would EXCEL at DE Days. So I would probably take that. Lower power, better learning experience driving.

Only Mich PS2's

jeanmarcboilard

They're on back order if you try and order them. Some guys might know where to get them, others have been looking for years. I might be wrong but I looked everywhere and couldn't find them. Ended up going back to stock turbo twists for that reason.

Dock

Then I'd suggest stock wheel and tire sizes.

Wealth Manager

R888: 305/30/19

R888's run wide. I run this tire and size on a 12 inch rear.

Duc Hunter

These for street tires? Hmmm

For use on the track right? I already have stock size wheel on the car...finding nice tires is a challenge. PSS's blow the PS2's away in terms of traction and longevitity IMHO...but are unavilable in 18". My though was 19"s for street, as I said, and if I do a track day an dont take teh Audi, throw the stock wheel back on.

Dock

No, for street use. OEM wheels with OEM size Michelin Pilot Sport PS2 tires.

BUTZI996TT

Where are you located? What suspension are you running and at what ride height? I would recommend sticking with an 18" wheel on the 996tt for a number of reasons. I build custom wheels for the 996tt and can help you get sorted. Shoot me an email info@butzigear.com so we can discuss some details.

Duc Hunter

Dock, appreciate that advise. I use to run PS2's and loved them....until I found PSS'....they blow the PS2's away. They last longer, they are quieter, and they have far better grip in the dry and wet. I won't go back.

I will shoot you an email. I agreed with everyone that 18's are more ideal. My challenge though is tires in any reasonable size are getting harder and harder to get. They re more choices in 19's. and since 99% of the driving will be street.....and Ia have another car for the track if I want.....hence my dilemma and question.

Dock

I don't at all like tire generated noise; IMO the PS2s are very quiet. They are also way more than adequate (outstanding in fact) for dry or wet street driving, including very spirited driving on curvy mountain roads (North Georgia, Western North Carolina, Eastern Tennessee). Unless the curves are extremely tight (like on the Tail of the Dragon) I have to hyper exceed the speed limit to even really push the limits of the tires. Certainly around the greater Atlanta area, where I spend the majority of my time driving, the PS2s provide way more traction than required. The fact that the are readily available in OEM sizes seals the deal for me.

YRMV

Wealth Manager

My car ONLY sees street duty and up to 180+ mph. Yes I'm crazy. lol.

R888's are very sticky. They will "hum" though once worn down some.

Duc Hunter

Dock, I am not sure where I mentioned tire generated noise...and I dislike that too. I also agree the PS2 is a great tire....it was my tire of choice...until the PSS. It last longer, has more grip in all conditions, is quieter and...did I say LAST LONGER? It knocked the PS2 down a peg IMHO.

Still no one has commented on how wide we can go up front, or out back, without needing to roll the fenders??

SelectiveRecall

I am currently running BF Goodrich G-force Rivals in the following sizes:

245/40ZR-18
315/30ZR-18

Very sticky tire and way less expensive than PS2.