So, it appears that no one (that I can find, anyway) is making track tires for this car yet, with its ginormous 245/35-20 fronts and 305/30-20 rears. And at about $2100 per set, going through a set of "streetable track & competition" tires, like the OEM PZero's (bleah) or Michelin Pilot Sport Cup 2's that I like to run, every 2-3 track days gets a bit expensive. Street tires just chunk out too fast on some of the (abrasive) tracks I like to drive, so I really think I'll get a bit more life out of a track tire that doesn't have so much tread to rip away.

I'm wondering if anyone has run the measurements to see if a set of 19" rims will clear the big 16" PCCB system and, if so, what size and spec rims and tires will match the stock sizes closely enough that they won't confuse the 991's finely tuned PDCC and all-wheel steering systems?

And, assuming one can match the car's expected contact patch with 19" tires, do the car's systems handle the additional traction track tires give?

 

Thread bump to see if anyone yet knows definitively whether a set of 19" wheels will fit over the 991TTS PCCBs?

Looking to get the car tuned with GIAC Stage 1 or II and GMG exhaust, but waiting to see if I can find an AP brake kit to replace the PCCBs as part of moving to a 19" wheel for the track.

 

Michelin Sport cup 2come in 265/325 also. They will fit 991 TS
Has anybody try this yet?otherwise , Dunlops are only option

 

That would be interesting to check. I'm not an expert, but those tire diameters are beyond the 3% deviation from OEM that I've heard as the suggested max for these AWD cars. Perhaps more importantly, the differences between your front and rear tire diameter are more than twice that of the recommended sizes. Knowing how finely this car's systems are setup to integrate wheel/tire behavior into overall performance at the fringes, that would make me a bit wary. At the very least, your speedometer will be wrong unless it's recalibrated. :-)

I also wonder if, given the 1/2" diameter greater front tire diameter and 1" greater rear diameter (along with wider profile), even if you didn't get some front tire rubbing at the locks a fender roll might be required to really fit the tire?

The direction I tried taking to make tracking this car a little more practical was to explore an alternate brake kit, which would allow both less expensive brake replacement and allow a smaller wheel (and thus, less expensive tires and more tire options). Alas, this is what my tuner heard back from AP for the 991 TTS:

"Thank you for asking but at this time we don't have much interest in making a steel conversion kit. The front disc has a super wide annulus (D74) like no other Porsche disc. Everything would have to be custom made including a batch of discs & at this time we just don't see enough demand to justify all the time & money needed to make this happen. So far, you are the only person to ask."

So, right now, while I love tracking the 991 TTS, between the PCCB and 20" tires, it's damned expensive (especially on the cheese-grater track I most often run on, which can chew up brand new tires in a single weekend); so in the interest of spousal harmony, I'm going to lower my consumables cost by picking up and lightly tuning either a 997 GT2 or a 997 TTS. :-)