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RA1's vs R888
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TOPIC: RA1's vs R888

Re:RA1's vs R888 16 years, 3 months ago #2125

rlofgren wrote:
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.


Rick,
This is usefull information thanks. At Miller I was looking at the wear on Jon Arino's and Jim Foxx's R888. Jon was running RA-1 pressures and ran over the edge of the triangle and corded the tire. There was still grip and rubber left on the tire. Jim Foxx was running more pressure, but no where near as much. We took Jon's tire to Bryan Shackelford and he advised more pressure. It was a guess as to how much. The idea after that was 40 hot or so. The 40-41 cold is crazy high and I still wonder if is too high. Maybe 42-44 hot is what we need. Did you check your hot pressures?
Joe Paluch
944 Spec #94 Gina Marie Paper Designs
Arizona Regional 944 Spec Director, National Rules Coordinator
2006 Az Champion - 944 Spec Racer Since 2002

Re:RA1's vs R888 16 years, 3 months ago #2126

whaxed wrote:
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.


What suspension and camber settings? I know that most underprepped cars roll over the sidewall alot more well prepped ones. My thinking is that for a fully preppared car running 3+ deg of negative camber 38 psi hot maybe better than even 40. I still think 40 cold is too much. What I do think is that this maybe a break through in the thinking with this tire so we can narrow in on the range. We may need to try 37 to 41 cold and just see how it works out. I really don't think any 944 guys have started that high with these tires before. If you figure we gain 6 psi cold to hot then a 37 to 41 cold range could be 43 to 47 hot. With the RA-1 anything over 40 hot was sliding around time. So I doubt many have tried 43 or even 42 hot.

My gut tells me to try 38 cold with my R888 this September. I will get some pictures of wear relative to the triangles on the side. I will also heat cycle these Saturday morning for 1 session and let them sit until Sunday. On Sunday I will run them again and hopefully get accurate hot pressures and temps.
Joe Paluch
944 Spec #94 Gina Marie Paper Designs
Arizona Regional 944 Spec Director, National Rules Coordinator
2006 Az Champion - 944 Spec Racer Since 2002

Re:RA1's vs R888 16 years, 3 months ago #2129

  • whaxed
  • OFFLINE
  • Drivers Ed
  • Posts: 16
front: 400lbs, turbo bars, no strut bar, 2.5 camber, bilsteins.

rear: 31 hollow, 19mm rear bar, smidge less than 2.0 camber.

Re:RA1's vs R888 16 years, 3 months ago #2130

Not a lot of camber there, that may contribute. Is the car understeering on the 400lb springs and scrubbing the front tires? It will be very useful to get tire temps across the tire while hot. This would go a long way to settle how we are using this tire. I plan to do that in a couple of weekends to prepare for Nationals.
Eric Kuhns

National Director Emeritus

2007, & 2008 National Champion
2011, 2012 2nd

Re:RA1's vs R888 16 years, 3 months ago #2131

  • whaxed
  • OFFLINE
  • Drivers Ed
  • Posts: 16
Yeah, that's intentional. After all the Miller reports when I was doing setup I was hearing more pressures and less camber, so that's what I decided to try, knowing that everyone's pretty set on the RA-1 config., and that wasn't working on the R888.

I'm not getting push but this was only my third event and I'm not wringing the car all the way out, so that might be driving style as well as setup.
Last Edit: 16 years, 3 months ago by whaxed.

Re:RA1's vs R888 16 years, 3 months ago #2135

The word from Toyo was the R888 need less camber. Well running over the sidewall is a sign of too little camber. I think for our suspenions we keep the camber the same bump up the pressure.

That is my take.

I will be running 3.5 as always and 38 psi cold. I will report back out they turn out.
Joe Paluch
944 Spec #94 Gina Marie Paper Designs
Arizona Regional 944 Spec Director, National Rules Coordinator
2006 Az Champion - 944 Spec Racer Since 2002
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