kgorman

FWIW, we raced all season on R888's. Our data shows that 34 to 36 hot is fastest, and that shaving them allows us to be fast out of the box all the way to about 25H/C and finally starting to cord at about 30H/C. If we ran full tread we would H/C out while we still had lots of tread left. Seems to line up with what Seth is saying. But there is much debate about what pressures to run the R888's at in the Spec Boxster world.

M758

Do you guys have problems with cording the outside edge or rolling over the wear indicator triangle on the side of the tire. We had 944 spec guy cord a couple tires running at those pressures. He had tire rubber and grip left yet corded the outside edge very badly. This wear pattern was completly new to the R888 and the advice was more pressure to keep from rolling over on to the tires's sidewall. Apparently from what we have been told the transition from tread rubber to sidewall rubber is less tolerant to roll over than on the RA-1.

That is on reason we are looking at higher pressures than when using the RA-1. Also shaving on the 944 spec has not turned out good results. So far full tread is way to go.

Seth Thomas

What track did you guys have this problem and how is the general tire wear at that track?

M758

The tires corded at Miller running the 3 mile outter track, but the same wear (rolling over the triangle) was noticed at PIR's 1.5 mile roval and Firebird's 1.6 mile main track. Miller was new to all of us, but the wear was normal on RA-1 being run on 944specs at the same event. Tire temps seemed to be similar too. PIR is our home track an d we have a good basis for wear there.

The latest 40 psi cold data came from Thunderhill. Some of this came from a Spec E30 driver who cranked out a really fast lap at T-hill before the repave. This e30 driver had been running times very close to the top 944 spec driver and when he found 40 cold worked and he also tried it.

I still feel 40 cold is too high, but may be shooting for 43-45 hot may be the thing for our cars.

Chris M.

What's the weight of the spec boxster? I thought jrgordon had poor results when he shaved a set.

AudiOn19s

What size tires / wheels are you guys running for Spec 944?

aeshultz

Audi;
I believe they (we) are on 225/50/15 on 15x7s. From memory.

AudiOn19s

Well there goes my idea. I was going to suggest that too wide of a tire on a narrow rim combined with lack of negative camber could have caused the tire to cord right in tht sensative area...but Toyo suggests a 7' wheel for that tire though.

I actually worried about issues like he was stating because I stuffed a 295 on a 10' wheel (285's weren't available when I got mine) but I've hadd VERY even wear and temps with mine running hot pressures in the 34-35 range. I'm only at 24 HC's currently so I'll see in the next 10 where the tires go. According to many they're right at the point where they're gonna fall off and strat having issues.

Andy

M758

Yep 225/50 R15 on 15x7's

Most guys running -3.0 to -3.5 to negative camber up front.

mark kibort

what is this "really fast lap" at thunderhill in an e-30?

In this case, depending on how fast he is running at thunderhill, it might be a matter of lower rolling friction for over inflated tires. However, i helped a bunch of guys that were all spinning off at buttonwillow and had one thing in common. 40psi cold temps on RA1s. dropped it 10lbs and they all felt their cars were handling better.

mk

earlyapex

I often ran 27 psi cold on RA-1's. I've since gone to 30 psi now that I use nitrogen.

pixrken

Hi Mark,

A 2:10 with the Thunderhill Turn 5 bypass and 2:11-2:12 with the Turn 5 cyclone would be consider good times for our cars in a race. Please keep in mind we're running a spec series where headers, chips, engine mods are not allowed and we have to be a minimum 2,600lbs with driver at the end of a race. At 2,600lbs and approx 130rwhp for our 944-spec cars you can easily compute our power to weight (or lack of it)
We know the RA1's very well since it's been the 944-spec tire for years, start at 30-32 cold with a target of 38 hot. We won't mind having the RA1's as our spec tires forever but the issue is we been ask by NASA/TOYO to transition over from the RA1's to R888's. I believe all Toyo sponsored classes were ask to do this, i.e. 944-spec, spec e30, spec miata, etc.
Our knowledge of the RA1's did NOT translate well to the R888's. We tried the R888's from 30-40 hot and they were consistently two seconds slower than the RA1's at Thunderhill. For example a 2:12 with the Turn 5 cyclone would be a 2:14.
The last weekend with starting at 40 cold on the R888's it was the first time we saw lap times go down to approach a RA1 lap time. The spec e30 did a 2:10 with the Turn 5 bypass and our guy did a 2:12 with the Turn 5 cyclone and felt after two laps it had just as much grip as a good shaved RA1.
Another one of of guys started with 38 cold on his R888's and ended up 44 hot, he painted a white stripe from the raised triangle sidewall indicator to the bottom of the tire, even at 38 cold there was some sidewall rollover as it rubbed off some paint from the triangle.
You can make the argument maybe the faster laps with the higher pressure R888's were the results of a newly paved Thunderhill track but if anything I thought we were slower because Turn 6 and Turn 8 where you normally put your left tire onto the apex berm now has a raised curb which can upset your car or bend a wheel.
This is just a FYI of our experiences, not a statement or argument that this will work for another car setup but for our 2600lb spec cars with our spec suspension and running 225x50x15 R888's on 15x7 spec wheels it seems it want 44-46 hot.

schwank

That's what I'm running on my car, with -3.5 camber. I found if I run the 888's at the same temps as RA1's (32c, 39-40hot) they feel more greasy at the end of a 30 minute race. I've backed them down a few pounds to 29-30c, 37 hot and they seem a little better. I've only run them a couple weekends so far though. I've chatted to several other folks at the track that are still working to dial them in. Most are still on RA1's though.

I'm trying to stay off the Hoosier crack pipe but...

M758

2:10 was the lap.

I have never run thunderhill so I can't say what it is like other than it is better than 944 spec track record and the 944 guy where I am getting the data from has the track at Miller 3.0 mile course set this past summer at our big 944 spec gathering and Thunderhill is the 944 guy's home track.

Still what you said may have some truth to it. The only thing I do know is that what worked for the RA-1 does not seem to work for the R888. Eric, I also have heard that when started at RA-1 pressures the tires can go away during a run.

Combining this data with the 40 psi cold stuff maybe the lower pressures are working the sidewalls alot more and overheating the tire. As such if you start high the temps stay more stable. The issue with going lower pressures may not cause the tire to go greassy, but may cause the tire to cord on the edge.

Tough to say for sure really.

earlyapex

The R888 on a 15 inch wheel is part of your suspension.