[FT]

There have been quite a number of discussions on almost all the car forums on R888 pressures, so I thought I chime in with my experience.

I have been in the opinion after doing over 20 track days on R888s that, for me, 34 front and 36.5 (psi) rear hot pressures worked best.

Last weekend we were at VIR, running full course. The weather was quite on/off rain/sunshine, so setting tire pressures before each session was at best a guest work. During the last day of the event, in the morning the track was soaking wet, I did not even go out. First afternoon session, the weather had dried up, sun was shining bright and we got on to a completely dry track with excitement. I kept the pressures from previous day as I could not even guess what would happen. Ran a great fun session safely, but car felt loose in the back on some fast corners, ABS would kick in at the end of front and back straights, nevertheless, it was great. After coming into the pits, I checked the pressures and as I suspected they were too high, 36 front and 41 rear. So, I adjusted them to the pressures that I liked for the final session of the event the same afternoon.

Last session, same gorgeous weather, went out ran as I did the previous session without trying any heroics or pushing too hard, even taking it a little easier on some laps and enjoying the experience. The car was much more stable especially under braking and uphill Sess and hog-pen. Came in to the pits, checked the pressures, they were exactly where I wanted them to be.

I don't check my lap times during sessions, but sometime in between. This last day of the event I did not check them at all. After coming home, I checked all the data I gathered and to my surprise the segment times and lap times were nearly identical between the two sessions; with higher pressures I was actually ~2/100th faster on my fastest, which is negligible, but still significant to note.

But the data also shows that with lower pressures my times under braking were shorter, I was faster through the uphill Sess, but I was slower in corner exits on slower corners, such as in T1, 4, 11, 14, 17. So, it all balanced out. However, I was a lot more consistent in both the segment and lap times with the higher pressures and actually a little more aggressive with the throttle.

So, as a conclusion, I have no idea what to do next event besides keep trying different pressures And, I guess the Cayman is not as sensitive to pressures and I believed it was.

If interested here are couple videos of the two sessions:

RacePak Data Overlay - VIR Full Course on Vimeo

VIR White Group Run on Vimeo

 

[BillL223]

Your results are similar to mine. I found no benefit to going to higher pressure. Try 32F and 34R. I got good temperature readings with this and stayed with it till the tires went away (heat cycled out). I'm trying Michelin Sport Cups and as mentioned in another thread, will try to get some data tomorrow.

 

[4by4]

With Stock suspension.
I run 36F 38R. I found with 36F 41R the back can slide more. With 31F 33R there is more grip but you have to drive smoother and you can get a faster times.
However your tyre outside edges last longer with the higher pressures, this may be a more important aspect.

 

[Capercat]

With Stock suspension.
I run 36F 38R. I found with 36F 41R the back can slide more. With 31F 33R there is more grip but you have to drive smoother and you can get a faster times.
However your tyre outside edges last longer with the higher pressures, this may be a more important aspect.

For street driving I'm running 37F 39R, is this too much pressure? I suppose 1 psi isn't a huge difference.

 

[4by4]

For street driving I'm running 37F 39R, is this too much pressure? I suppose 1 psi isn't a huge difference.

I was just refering to the R spec tyres here for the track.

For the road, I suppose what the plate says near the door, however the gen I plate said something completely different. Figure that .

 

[FT]

For street, I use what ever is written on the door, no need to change. I don't what gen II pressures are on the door, but 37/39 see awfully high.

 

[Capercat]

The door pressures seems too low IMO. I increase the tire pressure in an effort too prevent damage to the rims from our pothole infested Sydney roads.

Although I do find the front bops around a bit as a result. I may have to lower it a tad.