AudiOn19s

Seth,
Has the bimmerworld team found that you're faster or slower on the R888's once adjustments were made?

mark kibort

Sure doesnt seem that way based on their times!

archer ran a 2:15 at RA. a time that hasnt been scared up since the RS6 Audis ran back a few years ago at 2:14.

mk

Veloce Raptor

Wow, so you have found the exception? Perhaps his CAR was faster.

If you look at WCT results so far, times are generally slower.

Seth Thomas

So far this year most of the races we have been slower. Here recently I think things are changing. The cars require a little bit different setup approach with the 888s. We are finally getting to the point we have these tires dialed in and can turn fast lap after fast lap with them. They do wear more than the RA1s over the life of the race but they are just as consistent.

Side note: RA1s were known to be good for just one fast lap and then fall off about a second to two seconds after their first lap. These tires to begin with were the opposite. They seemed to get faster until the 4th lap and then stabilize. I think we have got the setup figured out to the point the 888s are only good for one fast lap now. Everything after is about 1 second off.

earlyapex

Seth,

Without giving away any secrets, how have you changed your suspension set ups to maximize the R888's performance? Have you had to change your driving style? Thanks.

Seth Thomas

Different camber, softer springs, and less air pressure are the big changes. Other stuff is minor stuff that only applies to our cars

M758

This is not intended as a dig at Seth, but the underlined statement is one reason I have never use speed WC data when It comes to the toyo used on the 944 spec cars. We never once experienced that kind of behavior with the RA-1. I do believe it was the experience in Speed WC, but it just nevered worked like that for our cars in club racing use. I guess it has to do with alot of factors. As such I don't know that Seth experience with R888 is totally applicable to the 944 spec nor club level race cars.

Frankly I never understood why the Speed WC guys had the experience they did with the RA-1 and I can only guess it comes down to the need to have speed right away and not really needing the tires to last more than race a distance.

mark kibort

and if you look at WC GT times, they are generally the same or a little faster.

probably a toss up.

mk

cgomez

This is exactly my same experience on RA-1s vs R888. On my Exige S with R888 I'm no way near my best times with RA1s last year, and now I'm even using lighter wheels.

I think the compound on the RA1s is better (slightly grippier and more consistent through heat cycles) plus the contact patch is much better when shaved as the R888 grooves are always there almost until the tire cords.

Seth Thomas

The RA1s and any tire out there are always their best (stickiest)when they are brand new. They will not get better with age. They do get more reliable with age though as they get harder after heat cycles. The RA1 and the 888 are both the same in this regard.

What I think is the difference in WC experience and 944 Spec experience with either of these tires is the difference in suspensions. The WC cars are solid suspensions with monoballs at every corner and suspension mounting point. No where in the suspension is there a rubber bushing. 944 Spec is the opposite of this. There is more play in the suspension of the 944 which doesn't yield 100% of the tire or as susceptible to heat cycles and full on grip like the WC cars. The RA1s all we could use them for was at most 5 HC. After that the tires fell off so much that we couldn't fine tune the suspension for grip anymore. Take these same tires to do some practice sessions for Club Racing or DEs and they worked perfect. Why is this? Because in these two environments the cars aren't driven to the extremes that a WC car is driven and the suspension does not have to be tuned as perfectly. When you have the entire field within 1 second of each other ever 1/10th of tuning makes a big difference.

With all of this being said I think the basic principles of tuning with the tires is very similar. The guidelines of what pressures to run, camber to run, and so forth is all applicable to whatever series they are ran in. What differs is the amount of use and how quickly they are gone due to the differences in suspensions, car weight, balance of car, racetracks driven, and most importantly driving styles.

M758

Seth,
I agree with the differences you stated in the cars. I believe that is what causes us to have a VERY different experience with RA-1. I ran 9-10 sets of RA-1s over the years and NEVER could I run as fast on new full thread or even 4/32 shaved new tires than I could with old tires near the end of their life. Time and time again the old tires would run faster lap times. I estimate that I would take me 5-6 heat cycles on 4/32 shave tires to get a similar speed as old worn 20+ heat cycle tires. I was not alone in this expereince as every 944 spec driver learned the same things.

Let make it clear I am not say that you are wrong, but our experience was different. So given that difference I always take Speed WC tire data with grain of salt. What works for you guys may or may not work for us. This was the case with RA-1 and I expect it to be the case with the R888. Interestingly the latest feedback I have with R888 on a 944 spec car is 40 psi cold. YEP 40 COLD. Word is that it took 1-2 laps for the tire to "come in", but when it did it was just as fast as the old worn RA-1s we love so much. This driver was never an R888 fan either, but does have a good level of experience and is one of the top 5-6 fastest 944 spec drivers in the country.

Seth Thomas

Nope I agree with what you are saying. My post might not have made that clear but I think you are valid with your points.

And i think one of the differences in what you are telling me in this last post is that you are talking about the difference of full tread Toyos heat cycling out vs. shaved Toyos heat cycling out. This is an apples to oranges comparison for both the RA1 and 888. A full tread Toyo will get faster as it cycles out for a lot of reasons but mainly because you lose the tread squirm. A full tread tire will need a higher initial PSI vs a shaved tire. All we run in WC is a shaved tire because this is the fastest. Just some notes of difference from your post above.

M758

With the RA-1 we ran the same pressures all the time. Be then full tread, shaved to 4/32 or nearly slick. They always gripped best when nearly slick after alot of heat cycles. Then at some point the grip would fall away FAST.


So do you think that maybe the tire pressure will need to change as the tire wears? Maybe start a seeming crazy 40 psi cold full tread and then reduce pressure as the heat cycles increase?

For us our goal in a spec tire is not so much outright speed, but a long consistant life span. This means that we can run the tires many weekend and still be fast. The RA-1's we would get 20-25 heat cycles in the "fast range" when shaved to 4/32. The first 5 were slow and after 25-30 they would drop off and lose grip. Between there however they would be fast and consistant.

Ideally the R888 would also allow for a nice plateau of peak performance for our cars. We really can get by if the tire is 0.5 seconds slower at that peak as long as get get good life.

The thing I get concerned about is the limit life numbers some guys are presenting. What I don't know however is how much that life may be impacted by the pressures and suspension settings used on the cars. There is still so much to learn about R888 that I am quite cautious to not to write off the R888 as inferior to the RA-1 before we really learn how to use it for our 944 spec cars.

Seth Thomas

I think for you to have a consistent life and speed out of the tire you wouldn't start it at a cold temp so high. I would think the tire would last longer and be faster if you were measuring a hot pressure. The main reason I can guess the high pressure worked for you on a full tread RA1 is because the tire at that point acts more like a street tire. It has as soft sidewall with a lot of tread. As the tread goes away the sidewall stays the same but grip should actually pick up. With this I would think you can get away with less pressure in the tire especially hot. With that starting pressure I would bet your tires are seeing 45-50 PSI hot. That is a crazy amount of air pressure in this tire. And hot is the real pressure in the tires because this is when they are being used. Cold pressures change depending on the weather unless you are using Nitrogen but even then it can differ slightly.

Do you know what the temps look like on the RA1 with these pressures?

The R888 is a different tire than the RA1. It does have a stiffer sidewall and a lot different tread pattern. The R888 with the stiffer sidewall does require less of a starting pressure then the RA1. The compound is different on the tires so I can't really say how long they will last. I do know that I used a set of R888s on an E36 at Road Atlanta a couple of weeks ago that were used from our WC cars (about 4 HCs). They lasted me all weekend and now have about 14 HC on them. They were as fast from when I put them on the car to when I took them off. The amount of grip offered by the tires was the same through out the weekend. They did wear a little bit more than I am accustomed to but they still had life in them after this point. And this was using a basis of a 35 PSI hot for a 235/40/17 R888. I didn't take any temps because this was for a DE so that wasn't as important to me. So the R888 I think is going to be as similar as the RA1 as far as speed and amount of life. The difference will be there is a learning curve with them at this point. They are not the same tire as the RA1 and guys are going to have to rethink how they tune with the tire. This is why I think the WC data helps your guys out. We can tell you the general direction we have to go to get grip out of the tires. You guys then have a starting point to work on to get the tires more tuned for your car.

M758

Seth,
I run the RA-1 at 38(maybe 39) psi hot for all conditions. Tire temps were 160 to 200 depending on when you took them and how hard the last lap was driven. Nearlly all of us have the camber dailed in for even temps across the tread. Starting pressures were 31-32 psi or so. I personally have yet to run the R888, but the 40 psi cold comes from another driver. He is fast and had been trying the R888 since April. Could never get it to run as fast as RA-1's in that nice plateau. He tried starting pressures from 30-40psi hot and was never happy. The last race out he got this wear pattern (notice the less dirt on the part just left of the center, but not all the way to the edge).



He got told by the tire guy that the tire needed more air and cranked it up 40 psi cold. This is when he got good grip results on a track he has lots of experience on. He could not do a back to back with RA-1 as he did not have good set left. He did not tell me hot pressures, but I have asked for them.

So clearly this different from your experience. Another interesting point is we have 2 other fast 944 spec guys on R888 that have had the outside edge cord. It cords right where the tread rubber transitions to the sidewall rubber. The issue appears to be running the tire over the little triangle where the wear indicator is. Run over that and you destroy the sidewall in time. They had been running 36-38 psi hot and will bump the pressures up to deal with this edge. So again more indications that we need HIGHER pressures than what we ran on the RA-1.

So as you can probably imagine this can be very conflicting data and it is tough to know what to do. I value your WC experience as I know you guys have put alot of effort in finding how to work with these tires, but I also get frustrated in that it just does not seem to transfer over.

The big concern for me is that we in 944 spec were quite happy with RA-1. We are a low budget series and the tire was nearly ideal for us. We did need to shave the RA-1, but the good news was that the benefits to that were wiped clean away after 12 heat cycles. Also they were simple to run, took all kinds of abuse and lasted for ever. None of us cared if they were slower than Hoosiers and their need for a "break-in" of 6 heat cycles was a minor issue and perfered to a tire that stated fast and dropped off. This way guys with money could not buy more tires to be faster. Amazinly I have known some fast guys to go "dumperster diving" in take off pile of our tire guy to get RA-1's to race on and take get a few more heat cycles from them and still win. Being cheap you just have to love that.

The R888 is new beast and the care and feeding is still a mystery.