40 cold ! ouch . but if Rick says it's good I will try it !

40 psi cold is crazy.. However if after 2 laps they "come in" then it may not be so bad. Was Rick able to run back to back with the RA-1's on the new pavement.

I wonder if the new pavement might have impacted how the car felt at t-hill. I know that Rick knows the track very well, but the pavement may have a big role to play.


Still a few more weeks till I try our my R888.

BTW... 40 psi cold = how much hot?

With RA-1 I would start 32 cold to achive 38 or 39 psi hot.

Was Rick at 48 psi hot?

Joe,

When we first heard 40psi cold we had the same reaction but none of the pressures we know from the RA-1's works with the R888's.
Rick was the first one in our group to try the R888's back in 4/20/08 in a PCA TT at Thunderhill. Please keep in mind Rick is very familiar with this track, running on it for years, was on our 25 hours of Thunderhill team last year and we had our series race on it 3/9/08. Nothing he tried (from 30-40 hot) on the R888's worked. He was almost two seconds slower with the R888's, swapped them out and instantly got back his time.
That's the reason why he took a old set of RA-1's to Millers instead of a new set of R888's and he gave the Toyo rep. an earful at Millers.
Rick ask me if he can start stock piling RA-1's back in June and I told him to please refrain from doing that.

Now to your question as did he try running back to back with the RA-1's last weekend on the newly paved surface and the answer is no. He didn't have any good RA-1's left.
I felt everyone was slower, not because of the new surface but because there were no fixed reference brake markers yet (they were all taken down for the repaved) and two major turns (Turns 6 & 8) where you normally put your left wheel on the apex berm now has high curbs which can upset your car or bend a wheel.

Perhaps Rick can comment the next time he's on this forum.

Ken,
Thanks for the update.

It has been my personal feeling that the R888 is not a horrible tire by any means. However we in 944 spec just have not be able to find the sweet spot for these.

Back in late 2002 we transitioned from the Kumho Victoracer as the defacto spec tire to the RA-1. Many growns were heard, but in a couple months we were all happy with RA-1. This transition is clearly more difficult, but when we went to the RA-1 we had lots of experience from other series on the RA-1. As such pressure were know up front. We used to run 32-33 psi hot on Victoracers and the 38 hot of RA-1's seemed high. However they worked well.

Sadly with R888 that data is sorely lacking. There is no clear body of knowledge as to what pressures to run and how we expect the tire to react to heat cycles over its life. As such it seems clear that some may not have a good initial experience. I do hope that in time we can learn what makes these tires work.

Rick's data is very helpful and a step in that direction. Starting in a few weeks I will have 3 more events in 2008 to test out the R888. I still have one good set of RA-1's so I will do back to back testing and share what I learn.

i was getting weird wear on the 888s so i took a tire down to AIM, our local tire guys. they said a spec e30 had a similar problem and it was all about rolling over the outside of the tire. then the e30 guy apparently used 40 cold, then 41 cold and did 2:10.x. we are usually pretty close to those guys on time, so they might be right. the tire guy said the sidewalls are stiffer, but the tread construction is the same as the ra-1, hence the need to do more pressure to match the sidewalls to the tread?!? who knows.

More General Info:

I was running 38 cold and ending up at 44 hot. I was still getting some sidewall rollover, which I think is a good indicator of how much pressure to run. If you get rollover on the wear markers then you might benefit from more air. When I ran the old lower RA-1 pressures I rubbed the wear markers off totally.

My car is a little underprepped, and a bit softer on bars so that may also affect what psi to run. A stiffer setup might be able to run a few less psi and not get the comparative rollover.