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From some research I've done,

-If you want to stick with 19" track wheels, most aggressive I've seen is a 19x9 and 19x10.5 with 265/35-19 and 285/35-19 RE-71R, especially the GT4 crowd. Yes you can go 19x11 in the rear with around +45-50mm offsets, but there's not really any tire choices available to keep a similar diameter.

-If you want to go with 18" track wheels, lots of peeps are using 18x9 and 18x10-11 with 245-255/35-40 front tires, which have more tires available. As for the rear, choices are still quite good with 275-295s.

If the track you are running does not have much straightaways, dropping to a 35 series tires is a good way to go especially since your acceleration is increased.

Also, if your budget allows, I would suggest getting custom spec wheels like 18x9.5 and 18x10.5 to run Yokohama A052s in the size of 255/275. (Yes, a 9.5" width wheel can fit the front if you have around -3.0* of camber using top hats and control arms)
A rough guide for suggested min/max tire section size based on rim width & diameter link:

https://www.tyresizecalculator.com/tyre-wheel-calculators/tyre-size-for-rim-size-width-calculator
 

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Correct, unless you switch to PFC calipers and rotors ($$$).
I thought the PFC kits ran supersized, @ 380mm rotors? Do you have any idea if 18" rims/barrels will clear a 350mm Girodisk brake rotor setup? Searched, but didn't see/find any forum thread addressing this.
 

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Discussion Starter · #45 ·
R-S4s not available anymore either.

Has COVID killed tire production? I'm getting legit worried about getting tires for the event next week. I may have to cancel.
 

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where are you ordering the nankangs from?

COVID has screwed with a lot of tire production (Michelin was out of Corvette rear tires for three months, Goodyear has been out of Hummer H1 tires even longer), but they're catching up. Some manufacturers who were planning on introducing new tires got affected by COVID during the transition and may not get the new ones out in time for the start of the season.
 

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I once read/heard that the manufacturers only make these track/autocross tires once or twice per year, as opposed to continuous production. If that's the case, it could simply be that all these sizes are out of stock, not permanently out of production. I don't remember where I heard/read that, but it seems reasonable.
 

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Discussion Starter · #50 ·
Most people agree the RE-71s are gone for good. I dunno.

The Goodyear Supercar 3s were actually pretty good. They certainly wore a lot better than the RE-71Rs. I wasn't timing laps this weekend but someone I was tagging along with did a 2:36, so that's very close to my 2:35-ish lap (harry's laptimer - 1hz gps so maybe off by up to a second)
 

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Has anyone considered using Nakang AR-1 on OEM size (8", 10") Carrera S wheels? I have a set in the cupboard so considering using them rather than buying another set of 19" track wheels.

The AR1s get quite good reviews and used by Apex on a lot of their cars:


In 20" closest AR1 fitment is as follows:

245/35ZR20 front (OD = 680mm, Rim width 8.5"), I think this is fine for 8".

265/35ZR20 rear (OD = 694mm, Rim width 9.5"), or
285/35ZR20 rear (OD = 708mm, Rim width 10"), best for rim width, but OD a bit large.

305/30ZR20 rear (OD = 692mm, Rim width 11"), best roling diameter but too wide for 10" rim.

The 285 looks like good fitment but do people think the 708mm OD is a little too tall/large and if it would impact on the gearing?

Works out to be +2% taller on OEM size, where the 245 is +1% taller over the OEM 235 size.
 

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Bumping this thread because there is a dumb question from the Cayman newbie.

With a regular (front engined) car -- or even with the 911 -- after exiting the track and heading back to paddock, I can pop the hood (or the rear engine cover in the 911's case) to help the engine cool down a bit. But with the Cayman, is there anything at all that could help to achieve the same goal? Jack up the rear and put a fan on the ground to get some air circulation in there?

As a bit of a funny story, one time when I was at the track, there was a track newbie in a 911. When he saw that most other people have popped and propped up their hood after pulling back into their parking spot, he joined the team and popped his frunk as well. 😬 I guess nobody explained the rationale behind people doing that to him...
 

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I do notice it gets pretty hot in the cabin at the track so I usually have the A/C running. Otherwise I always do a cool down lap plus a short drive out to the gate and back to cool the brakes and the engine. Then leave it up to the fans to do the rest which I notice usually run for a bit after switching the engine off depending on how hot it is.
 

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Bumping this thread because there is a dumb question from the Cayman newbie.

With a regular (front engined) car -- or even with the 911 -- after exiting the track and heading back to paddock, I can pop the hood (or the rear engine cover in the 911's case) to help the engine cool down a bit. But with the Cayman, is there anything at all that could help to achieve the same goal? Jack up the rear and put a fan on the ground to get some air circulation in there?

As a bit of a funny story, one time when I was at the track, there was a track newbie in a 911. When he saw that most other people have popped and propped up their hood after pulling back into their parking spot, he joined the team and popped his frunk as well. 😬 I guess nobody explained the rationale behind people doing that to him...
You'll get far more efficient cooling via the car's cooling system versus ambient air. As @don mentioned, definitely do a cool down lap at a minimum. If the oil temps are still high, slowly drive around the paddock if you can/want, or even just let the car idle while parked. The fans will pull air over the radiators to cool down the coolant, which will then do its job and pull heat from the engine. If you have a turbo, this is especially important as the turbo gets extremely hot and is cooled by the engine oil.

Final tip: do NOT set your parking brake after coming off the track. It will prevent the rear brake rotors from cooling evenly and can cause issues down the road. Get some wheel chocks if you have a manual and there's a slight incline/decline to prevent the car from rolling away
 

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Thank you for the reminder, Don and Phroenips! I'm a long time track rat myself, although I am new to owning a Porsche. Cool down laps are definitely something I always do because the local track is pretty hard on brakes, so keeping those brakes happy is quite important.

While we're at it, would you care to remind me what kind of oil temps I can expect during track use? I'm sure searching the forum will dig up something useful too, but if you can remind me here, I would appreciate that. 🤜🤛
 

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In my GTS [2.5T] (meaning I have the third radiator), at altitude (High Plains Raceway in Colorado), I'll see 235~245ºF or so while in Sport or Sport+ mode. That's even with back to back 25 minute sessions (with a co-driver in the other session). I use a good quality oil (RedLine 0W-40), and with that, I personally wouldn't start to pull back until it gets above 250ºF or so.
 

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On my PTPA running on my GTS which I assume reads data from the cars OBD system, oil temp ranges from a constant 241 on a cooler day to 248 to 255 on a faster track on a hot day and I've read up to 260 is not unreasonable for track work. With that said, I change my oil every six months these days or after six track or so track days, in addition to the PDK oil which I notice also gets almost as hot as the engine oil. During sessions I tend to keep more an eye on tire pressures rather than oil temp as I figure the car will let me know if it is running too hot!

I know some of the S guys find the CPU detunes the engine at around 240-245 anyway so does not let it run hot, whereas I reach 255 without any noticeable loss in power down the straight.
 

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So 235 - 255°F / 112 - 124°C range for oil temps in your GTS. Mine is a base model, so there is less cooling but it is also a smaller engine. I wonder how that'd change things.

Thank you for the tips again! (y)
 
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