R888 Questions
 

I've put R888s on the 997.1S I just got, and most likely will be tracking the car soon at VIR. My first time tracking this car, and first time using R-comps.

Some questions to those who've used R888s:

- How many track days do you get out of them?

- Do they typically wear down first or heat-cycle out first?

- If they heat-cycle out first, what are the symptoms? Big drop in grip? Abrupt breakaway?

- Is it safe to say that street use won't heat-cycle them out? Any other concerns with street use (besides howl at highway speeds)?

- I'm thinking hot pressures of 33 front and 35 rear, then adjust from there. Sound OK?

- Any particular ambient temp below which grip drops off sharply?

- How are they on wet tracks?

I've been averaging between 7-10. Car was pushing a lot so fronts were wearing out much quicker.
I found them to be better on a damp track than the Conti DWs. Contis may have dried out some so maybe that was the reason??? I even drove home from the track with almost no tread left in light rain and the grip wasn't bad. But if it's raining hard they aren't going to displace much water.

Yikes -- a lot of meaningless questions to ask since you already bought/ installed them! You will have answers to almost all of them in a track weekend or 2. Why confuse the issue now with these questions, and have doubt in your head while you are on the track? Many of the questions above will depend on chassis and driver inputs....

My only usueful comment is it's silly to have unbalanced hot pressures like that. The only reason is if you have a chassis set-up issue that can only be addressed by staggering the pressures (i.e., sways, spring rates, etc. may be off). The tires have a sweet spot where they tend to grip best when hot, and that is a relatively narrow pressure range. What should that pressure be? Dunno -- try a couple different ones and see. I've heard claims that it is anywhere from 26 - 38 psi... Highly car set-up and driver input dependent.

Not meaningless questions to me, I'd rather go to the track knowing more rather than less about what I'm working with, especially since the temps will be fairly cold.

I'll experiment with the tire pressures, including trying equal front and rear. Recommended street pressures from Porsche are about 6 or 7 psi higher in the rear, so I was considering maintaining a small front/rear difference for the track.

:shock: Stop that!!! I have money riding on these types of questions! And right now I'm look'n good for a big payout! ;) !

Tire preferences are highly subjective and dependent on car, driver and set-up and truly DIY. Your starting points for pressures seem in the park.If you have fun you got it right. There are no DE championship points :roll:

Levitas summed up tyre presures nicely for street, DOT and slicks at the instructer refresh weekend before last! If you missed it, you missed a great session!!!

^yes!^ DE. Drive, survive and have fun.

Other than roughing in based on tire build the best pressure* is car and suspension Dependant. What MikeL said but better said with more info was the tire is an active part of the suspension system and the effective spring rate of the car and the effective spring rate of the tire need to match up. too much delta between the tire and car spring rates will make for issues. Too much pressure will make the tire bounce and overpower the springs and dampers. Kind of like a dribbling basketball. A properly sprung 2000 pound car with XXX/XX tires will not want the same pressures as a 3800 pound car on the same tire.

I was disappointed** in the R-888s. The grip fell off fast and the cost was almost the same as well liked r comps. Lots of rubber left not so much grip. (I run hoos 50+ heat cycles tapping out best laps in 40+ cycle ranges and still felt the 888s grip fall off in under 15 HS). Near same cost as hot lick R comps but don't wear like some of the less grip/more life compounds. What is to like? some folks buy them for rain tires but the Hoo wets are the hot lick there. Most people run the pressures too high on the 888s. Start low and stay as low as you can, tune with temps across the carcase only going up if the centers are cooling off.

* Pressure is hot pressure. How to dial in hot pressure is but one Google away.

** "disapointed" means I wanted to cut them off with a chain saw and set them on fire.

I'll take a crack at a couple of these with the usual disclaimer that the following opinion should be considered internet chatter.

I have never used R888, but I assume that like any "summer only" tire, it does not cold weather. Cold and wet is likely worse. How cold and how wet, you might ask. I have no idea. At full thread, they are inters on a wet track in the summer. Not likely very good if the track requires full wets. I will not drive them (or anything) on a cold wet track. Heck, my days of track driving in the rain are actually over on any tire.

IMHO, street driving typicaly does not heat cycle tires.

Why are you thinking 35 R and 33 F? A lot of people run these tires on your kind of car. Why not search on some websites or ask the guys at Radial what they recommend. They paly around from there to see what works for you. I run 38 on both Nittos and Hoosiers DOT R-compounds. Many prefer 4-5 degrees less or a couple of degrees more on Hoosiers.

Good luck

My experience is they work the best in the 36/37lb range hot front and rear at warm or hot ambient temps. Colder outside temps require a higher cold starting pressure. I start with the rears 2lbs more than the front. Your car would be reversed.

When they get overheated they slip a little more, but backing down a little brings them back. They wear out more like the RA-1s then Hoosiers in that you can drive them down to the cords and still have some grip. Hoosiers and other slicks can, as you indicated, cycle out before the rubber is all gone (although they are fun to drive on ;) )

Can't help you on the wet characteristics . . . don't drive on wet tracks anymore.