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. 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.

Hi Joe,

Thanks for taking the time to do this and take pictures.
Your 46 psi hot is in line with what NorCal experienced for the R888's and I know it was controversial when we first suggested this because everyone was so use to 38-39 hot with the RA-1's.
Your times of 3/4 to 1 second slower for a 1.5 mile lap is also interesting because Rick experience 2 seconds slower on a 3.0 mile Thunderhill lap when he first tested a brand new set of R888's in a PCA TT event (compared to a optimal heat-cycled RA-1's). He tried adjusting the tire pressure from 36-40 psi hot and no luck in bringing down the lap times and gave up.
Rick might be at a good heat-cycle range when he ran a comparable RA-1 lap time at Thunderhill on R888's on approx. 46 hot. I don't know how many heat cycles he had in the TT event before he gave up on the R888's, I know he raced one weekend at Infineon so if you count practice, qualifying, race as three heat cycles times two days that's six heat cycles plus the TT event.
We'll have to do another test with a new set of R888's vs a set of heat-cycled R888's at 46 hot.

btw- a new set of shaved RA-1's is also two seconds faster than a new set of unshaved RA-1's at Thunderhill, don't know if this applies to R888's.

Thanks for the info, Joe. Watch wear in the middle of the tire- we've had some cord there as well.

Hey Eric,

What tire pressures were you guys running with the R888's?

Joe,

Thanks for your controlled characterization of your new R888's. Really good information to expound from...wish I had documented the wear on my tires as well as that.

Eric, Ken,

I also experienced some cording in the middle of my R888's.... 38 psi cold, -3.2 camber front, -2.2 rear with fairly even wear across the tires. Unfortunately I don't have any hot tire pressure readings.

Ken, the ones that carded that way were driven by friends of mine - not sure what pressures he was running.

For Nationals, I had the tires shaved to 4/32nds. I don't have my car around now to take pics of the tires (it's still in Ray's trailer 90 minutes away). Shaved, they seemed to tolerate low pressures well. Ray has a shaved set with over 10 heat cycles (including two enduros) that is wearing evenly running pressures of 28-29 cold. I've been following the high pressure school of thought with interest, but thought I'd investigate the other end of the pressure spectrum. Low pressures seem to be working OK with shaved tires so far, but it's still pretty early.

Nationals provided some interesting data. Ernie broght RA-1 to Nationals which helped him put down the fastest times of the weekend by over 1/2 second the very 1st day vs. any R-888 times the remaining 3 days. Ernie ran full tread R-888's on Saturday, which were about 1 second per lap slower than the the times he posted the next day in similar conditions on shaved R-888's, but still a bit more than 1/2 second slower than his times earlier in the weekend on the RA-1's. I can see why he wanted to run the RA-1's (had to force that issue for Nationals). I ran Nationals at 28 PSI cold.

I was again 1.5 to 2 sec quicker on top-tier R-comps (Hoosiers this year instead of Hankooks) vs Toyo's FWIW.