Hi guys!

So I tried to get some feedback in the 996 section of the forum but got dead silence... So I'm trying it here. My car is a 996 C4S with shorter springs (H&R). Everything else is stock... I have a dedicated set of wheels for the track. Stock wheels, Stock tire size... Camber is at -2.0 Rear and -0.7 Front (changing to -1.4 soon in hope to help understeer).

I was reasonably happy with MPSC running hot 33psi Front, 37psi Rear. A little bit too much outer wear maybe but reasonable...

Got a good deal on R888 (Full thread, brand new) so decided to give it a shot.
Can't figure out what pressure to run them...
Did a WE on them and settled at 37psi all around but I'm not sure that works well still... Something doesn't fill right, in particular towards the end of the sessions when being more aggressive and temperature gets higher I guess.

Also, I have absolutely no wear on the inside of my fronts...

HELP !!
Can you post the pressure hot that works for you??

Txs!

 

That's the $64,000 question. Varies between cars and drivers. I would post your question in the DE and Race Forum on Rennlist, a lot of trackers there. I try to keep them around 38 hot when at the track. But others I have read about vary from 35 to 42 hot.

BTW, I had my rear camber set at -2.08 rear and ate the inside edges of the rears badly on track. Had to dial it back to -1.5. The fronts have worn very well at -2.25. Rear weight must cause the difference.

 

it depends on the sidewall construction of the tire. But I usually start high and go lower. Ideally for my driving style it seems to point at 32 hot front and 35 hot rear. It varries depending on the track, if its slow or fast course, depends on the weather, and it depends on the tarmac. I see a lot of pp running really high tire pressures and i think that is the route cause of why they are not extracting the most out of the car.

But it really depends on the driver, car setup - the stuff i mention up top. but yea, the more track days the more of a 'feel' you will gauge of what tyre pressures to run.


which track are you going to ? Laguna ? infenion ? thill ?

 

I haven't run them in a while but I was around the 32-33 mark (hot). Best thing you can do when it comes to tire wear is be very diligent in monitoring it.

As soon as you pull of track without any delay measure your pressures so you have an accurate reading of how hot they really get on track.

Also a good idea to get a pyrometer. There will be a substanial amount of cooling that occurs to the tires even as you are doing your cool down lap and as you pull into the pits, but the idea is not to get a 100% accurate reading of the race conditions temperature, but instead to see the variance of temperature from the inside, center, and outer tread. Ideally you want all of the temperatures to be as close as possible. If the inside is 10 degrees hotter than the outside that's also quite reasonable. If its anything more dramatic then you need to adjust your suspension (camber/toe) so that you get even temperature wear.

Also depending on the number of track days you do a year your driving may improve by leaps and bounds and soon you'll see that the camber you used to be running is now not keeping up with your driving, so again you will need to adjust it.

Use what people say on forums as a reference point but don't short change yourself, get the PSI readings when you get off the track, and also measure your temperatures.

Alot of guys run so much camber that they never use and waste tires because they think more camber is better. Well if you aren't generating enough G's to load up the tire correctly that negative camber just creates a smaller contact patch and it'll make you pay for rubber twice as fast.

On my 997TT I noticed that with non slick tires (Bridgestone RE-11) -2 front and -2.1 rear was about where I needed to be to get very even tire wear & temperature readings.

There'll also be a level of understeer that you wont be able to dial out because you have an AWD, you'll minimize it certainly, but in slow corners when you change directions quickly it'll get exagerated compared to lighter cars with less weight. To some extent I think the main hinderance isn't even the weight in the front, so much as the overall weight of the vehicle (assuming you haven't gutted your interior, etc.).

 

We run them at 30 - 31 hot.
We have run them higher, and the grip and handling are not as crisp.
We have crewed w the WC teams, and they run them at 30 hot, and then play w it from there depending on the track conditions.

 

Fotostars, 33/37 is the sweet spot for C4S... I have run these for a few years now, if pushing on (depending which track) they will start to go off 12-15min into session and you will have to back off a little. Don't compare them to Cups, TBH the Cups are a slightly better tire, but the 888's are value for money.

 

My friends GT3RS runs them at 32/36

 

38 hot all around works best for me. at full thread they feel slippery. i had them new full thread drove to TH as "break-in". the entire day at the track was nerve racking. so, be extra careful with these new. i agree with stevo on when they start to go off except with me it's ~15-20min into the session.

 

Stevo,

I have a pair of Mcups, and I have to say mate- they do not inspire confidence like the 888's. On my track wheels I currently have V710's which i like quite a bit!

 

Have you tried them at lower pressure? I have recently used them for the first time, full tread, and at around 32/34 they felt fine, much higher and they got slippery. I also agree with a previous post, and prefer the R888 over the MPSC.

 

I like to run my Toyo R888's at 32 psi hot. This was the recommended pressure by Synergy Racing when they set up the suspension on my GT3. These tires seem to have their maximum grip at these lower pressures. I ran with Chin motorsports up at VIR last fall. Everybody with GT3's and the R888's were comparing notes and the group consensus was to run these tires at 38 hot. Kerrigan from Synergy racing told me not to listen to this "paddock talk" and to keep my tires at 32 hot. I ended up passing all those GT3's that day.



Dan

 

I love experimenting with Tires, honestly you would laugh at my selection, 888's, Cups, Corsa's, Hoosiers R6, Pirelli Slicks, Pirelli Wets and Dunlop Wets... IMHO without doubt the best road legal Track Tire is the Cup followed by Corsa and then 888's... They are all good Tires, but as I mentioned above once you start pushing these triple 8's you will start to know all about it... Cups are horrific in the wet maybe this is why they are so good in the dry, where the triple 8's are pretty good in the wet.
I take 3 different sets of wheels/tires along when I track the car.

 

To add.. I would run Competition Slicks & Wets at a similar pressure compared to the triple 8's, Cups or Corsa's... If I remember correctly 30/32.

 

100% agree. That "paddock talk" I always laugh when they tell me i'm running very low tire pressure and I should crank it up. I run a bit higher in the rear so my toe in does not wear my tires quickly at the track. But low 30's depending on weather. In the wet, low 20's

 

Yep, yep, and yep... Also Buttonwillow...

Thanks for the data point!