M758

I put this together for the 944 spec guys on R888, but some here may find it usefull. I have another race Oct-4,5 and will share more observations and photos after than event.

Basic chassis data
Tire size = 225/50 R15 at all 4 corners.
Car weight = 2625 with driver
Car power = 132 whp (maybe less)
Camber front = -3.5 both sides
Camber Rear = -2.5 both sides
Spring rates 350lbs front, 30 t-bars rear. (335lbs effective rate)
No changes from running the RA-1s
---------------------------
I ran my R888 for the first time this past weekend. Track was PIR and my home track and highs were 100F. This is normal for September. I also ran RA-1 this weekend to compare the times and feel. PIR is most a left turn course and tends to put extra wear/heat into the right side tires.


Firstly I ran the R888 starting at 38 psi cold (left) and 39 psi cold (right) on Saturday morning. These came to 46 psi hot on the left and 48 psi hot on the right. I pulled these off the car let them sit for 24 hours until Sunday when I ran them again. Photos are show after one heat cycle. Notice I am just close to running over the triangle on the side wall. The tire felt ok, but a bit slick. A slick feel is somewhat normal for the first session in September at PIR. Lap times were well off the pace, but again this normal for this session. I put on 14 heat cycle RA-1’s running at 38-39 psi hot and picked up one second. Some of this due to track and driver warm up. The RA-1s’ felt stickier.

Set of 4 (shown from rear in position run on the car)(link below picture is full size image)

http://members.rennlist.org/m758/HC1-Set-46-48psi.jpg


http://members.rennlist.org/m758/HC1-LF-46psi.jpg


http://members.rennlist.org/m758/HC1-RF-48psi.jpg


http://members.rennlist.org/m758/HC1-RR-48psi.jpg


http://members.rennlist.org/m758/HC1-LR-46psi.jpg


Sunday I ran the R888 for two more sessions. I had bleed them to 46 psi hot on Saturday and left them at this pressure for Sunday. Starting pressures were 38 and 37 psi hot (L & R). Ending pressures from the first session were 47 psi hot all the way around. The tires were run again about 90 minutes later. Estimates for speed were about ¾ to 1 seconds slower than RA-1s at this time. This is for a 1.5 mile 1:15 type lap.

Photos are shown. (link below picture is full size image)

http://members.rennlist.org/m758/HC3-LF.jpg

http://members.rennlist.org/m758/HC3-LF2.jpg


http://members.rennlist.org/m758/HC3-RF.jpg

http://members.rennlist.org/m758/HC3-RF2.jpg


http://members.rennlist.org/m758/HC3-LR.jpg

http://members.rennlist.org/m758/HC3-LR2.jpg


http://members.rennlist.org/m758/HC3-RR.jpg

http://members.rennlist.org/m758/HC3-RR2.jpg


Overall wear was ok. I believe that we cannot run the tires at hot pressures lower than 46 psi hot. Doing so will cause the tire to roll over the triangle and wear down the sidewall/tread rubber edge and will cord in a short period of time as we have seen on at least two other 944 spec cars. Grip so far seems less than RA-1’s in their prime. These tires were run full tread and there is not evidence of tread squirm similar to full tread RA-1s. It is hoped that the grip improves similar to a shaved RA-1 once 5-6 heat cycles are completed.

jrgordonsenior

I can't imagine running R888's at those pressures. I did once and almost slid off the track. I run my 2700 lb Boxster w/driver at 34 -36 hot all around and -3.1 fronts, -2.7 rears. I had the fronts at -3.6 but they handle better with less camber....

cgfen

Thanks
Very timely info.

cheers

Craig

TheOtherEric

Wow, I would have written a very different review myself. I run around 36F/40R, sidewall triangles be damned. I haven't gotten the horrible sidewall wear like the RA1 did.

And the R888 are awful for the first several sessions. Like the RA1. Sounds like you found them ok. But I did find overall life to be improved.

schwank

Holy crap. In the 3 days I have run my R888's, I cannot run them over 39 hot or they get insanely greasy. I have not rolled them over at all.

I start them around 32 cold here in Portland to get them to 39ish hot. Basically about 2psi lower than I run the RA1's. I'm not as experienced as you but I find them to grip the best for me around those temps so far.

Edit: -3.5 degrees of camber on mine

M758

Well we have had two guys run hot pressures down where we ran the RA-1's. They tires lasted for a while, but corded right at the edge with lots of tread on the center and plenty of grip left. For some reason on our cars they roll over the side wall alot more easily. The old RA-1s would never run over side wall at even running 34 psi hot.

Maybe given our tallish side walls the stiffer sidewall is more prone to rolling over vs shifting sideways. Maybe this allowed the RA-1 to still on on the tread rather that on the rubber of the sidewall. Once the R888 does that it will cord in short order.

As for running lower pressuers I think running lower than 46 hot wil cause the tire run over the triangle and then endanger sidewall. As for getting greasy. In the 3 sessions I ran them all were 20 minute practices. I did not feel any reduction in grip during the runs. They tires do feel a litle more sensitive to over heating. With RA-1 and lurid slide would result in a slightly overheated tire that would not grip ideally for the next couple turns. On the R888 that same slid seeming took longer for the tire to cool and regain normal grip levels. Maybe 3-4 corners instead of 1-2.

Now I am happy to hear that you think the R888 got better after a few heat cycles. With the RA-1 shaved to 4/32 it always took 5-6 heat cycles before the tire "got fast". Having just 3 on the R888 I would hope I am in that slow region still, but really don't know if that is still the case with these tires.

As for life... It is way to early to say.

333pg333

Yeouch! Wow that's high pressure to run. Maybe with the taller sidewall, but we start on a warm day with approx 25psi cold, get to 34-36psi hot and that's it. I run 255/35 18 f & 285/30 18 r. Car is about 2900lbs. 951. No excessive wear on the sides through rollover. I'd talk to a tech at Toyo just to check with them what they suggest.

M758

I have been told to not run over the sidewalls (triangles) as it could damage the tire. I have also seen the resulting damage when you do.

What is interesting is that every 944 spec car I have seen will run over the triangle at lower pressures. Hey it is not like our cars are very heavy nor powerfull. The only think odd is we run a tallish sidewall. Even the 7" wheels are fine for a 225 tire.

Alan Herod

My observations are from my rear tires on the 2450 pound (dry) 911, 255/40-17 on 9 inch rims; -2.0 degrees camber -- starting 30 psi cold shooting for 38 psi hot. On third set of rears so far. On last set I failed to bleed pressure between sessions, hot swap on pit lane. Tires went to 42 and chorded center. .. No evidence at any point of sidewall roll-over, even starting with 30-32 cold pressure.

Full tread 888s are no where near as unmanageable as RA1s; but, do seem to go off in the final sessions of their life.

adfsouth

My R888s get pretty slippery when they get to around 40 psi hot. I try to keep them 36F / 38 R hot. One time at Sebring the rears got up to 42 and they were so slippery that I had to pit and bleed them. Try using lower pressures regardless of the tire roll.

jrgordonsenior

Why do you think that? We also run 225's on 7" fronts and find they're to narrow for that rim. Toyo says 7-1/2 for that size. Hopefully we're going to 245's on 8-1/2's all aorund in Spec Boxster next year...

I've also heard the 225's have a stonger/different sidewall construction than the larger 245/255 sizes and that's why they cost $20-$25. more. Have you ever heard this?

RedlineMan

Joe;

Keep coming with the reports. I am quite pleased to be cycling in a brand new set of RA1s this weekend at Calabogie, but I am dismayed to note that it will be my last.

I will probably have to bite the R888 bullet after these beloved RA1s die their slow steady sweat death. By then, I hope we either understand these new tires, or Toyo makes them as good as the RA1.

FWIW, My tire supplier (Vilven) is also supplying GrandAm. They report these tires being faster for nearly everyone in the field, needing slightly less camber, and slightly less pressure. How long they last is another question that he did not have an answer for.

Beyond my emotional self, my imperical gut says that - all things considered - Toyo made a mistake here. Alas... most companies don't understand their customers well enough to grasp the concept of "if it aint broke". Making a faster tire at the expense of longevity is NOT what the majority of their customers want.

todinlaw

Joe, a comment and a question. Comment, can you run more negative camber to offset the rolling of the tire. Toyo says the tire should be run at 40 hot and atleast -2. or more camber. If you can just camber the tire our more to get your tread more even.
question. I have been told that the R888 does not need to heat cycle cure like the R6 what is your guys take on that???

JW in Texas

Joe,
I think you are right that your taller sidewall is affecting how they wear compared to our cars. Also, your spring rates are lower which is allowing the car to roll over more then we do too. You need those higher pressures to keep the sidewalls from rolling. Size wise, we run 225/45/17 front, 255/40/17 rear. We are running -3.0 camber front, -2.7 rear, fronts 34 hot, rears 32 hot. Spring rates are 450 front, 500 rear. We see no degradation of the sidewall/triangles & have been getting outstanding wear. The tires full tread do start to improve @ 6-8 cycles. We are easily getting 2+ weekends out of them & like JR said, if we can get 245s approved all the way around, we should be able to up that to 3+. Thanks for the write up

AudiOn19s

The more 888 threads I read the more confused I get.

For example. I'm running 255/40/17's on the front of my 996, 3100lb car, 450lb front springs and bigger than stock front sway bar. I actually found that -3.1 degrees of camber was too much for my application with these tires. I'm wearing the inside edges considerablyfaster than the outsides and I only use them at the track, no driving back and forth on them. Obviously no issues with rollover on the triangle. And before anyone says it, I'm no Mario Andretti but I"m certainly not putting around the track on a sunday drive either.

I run 295's in the rear @ -2.5 degrees of camber and they're wearing perfectly even.

Also, for me I found 35-36psi hot to be the sweet spot.

It's just crazy how everyone's experiences are different with these tires.

One thing I will note. Mooty pointed out several times that around 25-30HC's in they will go from looking like they have pleanty of life left to wearing very quickly and starting to go off grip wise. Coming from RA-1's I was skeptical of this BUT he's exactly right. My fronts have about 10HC's more than my rears do and are now at about 32 heat cycles and I can tell there's considerably less grip at the front now than there used to be. AFter about 25 heat cycles is when the wear started to speed up dramatically and the "too much camber" issue in the front became more apparent. Or maybe the lack of front grip is not allowing me to load them now like I could earlier in their life which is why the camber wear is showing up now???...I really need to get a pyrometer!

Andy