Toyo R888 Wear

#81

After finally accepting that 888s do not respond well to high slip angles, I focused this weekend on trying not to slide them as much. My driving style (like cobetto and j. allen) is high slip angle (drift). It was very difficult to adapt. If I drive the way I am most comfortable, they dont last 5 laps :frowning: . Its frustrating to have to change my whole driving style, but it looks like I’ll have to.

#82

[quote]donstevens allenr wrote:

I have heard of guys in se30 putting much less camber on the right side tires to give them more grip in left turns (most turns are left turns).

Most turns are Left? You running Ovals? Any track I can think of, mopst turns are right.

Don [/quote]
Oops. You’re right. Most are right turns so you want more camber on left side and possibly less on right side.

#83

Heat cycles

heatcycles_TGPR_photo.jpg480x640

Here’s some data from 10/11 & 10/12 at Talladega Gran Prix Raceway, a 1.4 mile, mostly counter-clockwise circuit with very abrasive asphalt. Probably not quite as bad as the old spots at Kershaw, but way worse than MidO or Road Atlanta. In a SE30 it is a 3rd & 4th gear track with 3 hairpin/carousel turns.

I started the weekend with my NASA Champs tires with +/- 11 heat cycles (test day and the dry sessions for P, Q & R at Mid Ohio). I added another 10 heat cycles at TGPR. They were shaved to 4/32 before MidO.

Cliff’s Notes:
Ran 28ish cold up to 36-38 hot. I didn’t collect a ton of temp data (my wife really didn’t see the fun in that) but the temps I saw were at the low end of the recommended range of 140-220. Mostly 130-160. I think the temps may be low because I was running my smooth-grippy pressures (counting on track grip to raise pressures), not my crappy-Alabama-asphalt pressures.

The car was balanced, but I felt like I suffered from general lack of grip the whole weekend. My butt-dyno is not that well tuned, but I don’t think the tires are entirely to blame. I was making a concerted effort to NOT slide the car around to maintain a lower slip angle as has been recommended. Also, I was trying to adjust my line to avoid heating the LSD or spinning the inside rear.

TGPR is definitely a handling track, but I was able to walk away from my friend in my Miata on year-old Hoosiers.

Tire Wear:
After Mid-Ohio, we decided to take some camber out of the right rear to help better put power down out of right handers. Unfortunately, we decided to make that change (and a full re-scale and align) before I decided to drive TGPR. We also put in our Road Atlanta wedge (50.4% RR/LF, I believe) for that right-turn dominant track. Unfortunately, TGPR is left-hander dominant. Maybe that explains why the car felt like it didn’t want to turn. Also, in spite of rotating tires side to side the rears were showing way more wear on the insides than I would like to see. The fronts are more evenly worn and still show a hint of tread pattern. Again, these are 4/32 shaves with 21 heat cycles averaging probably 25 minutes per cycle.

Questions I haven’t answered:
Do R888s drop off significantly after only a few heat cycles? I don’t know. I didn’t do any back-to-back comparisons between my new set and my old set. But the stopwatch didn’t show an extreme drop off. Some of the reviews I have heard make it sound like the car is absolutely hooked up with 2 heat cycles and undriveable at 8 heat cycles. I don’t know that I could blame more than 0.5 sec on a 1:10 lap on the tires going from 11 to 21 heat cycles.

Do I need to take out some rear camber? The tire temps were relatively even, but tire wear would indicate that I still have too much camber in the back. I think more testing at a temp-friendly track would go a long way toward answering that question.

The search for enlightenment continues…

Steve D.

#84

[file name=rear2.jpg size=78198]http://spece30.com/media/kunena/attachments/legacy/files/rear2.jpg[/file]

Sorry - I messed up the photos. Here is a rear 21 heat cycle tire… (other photo might be attached, hell I don’t know).

Rear

rear.jpg480x640

Steve D.

#85

Sorry for the multiple posts. I ain’t too good with 'puters.

[file name=front2.jpg size=79855]http://spece30.com/media/kunena/attachments/legacy/files/front2.jpg[/file]

Front tire

front.jpg480x640

#86

Steve it is good to see 20+ heat cycles from these.

I have 9 heat cycles on my full tread R888 and they still have lots of rubber on them. For me they just seem to be getting faster, but some that could be that I am learning how to use the tire better.

#87

Ok. So after reading the numerous threads about the R888 on here it seems the best course of action is (correct me if I’m wrong here):

  • Buy shaved - they seem to last longer that way
  • Low tire pressure (27-28 to start)
  • Try not to slide around for better grip and longer life

This is my first season and I’m looking at ordering these today or tomorrow. I was going to get full thread, but it seems like that is not the best way to go. Keep in mind I’m not trying to win, just don’t want to be last and also get as much life out of them as possible.

Thanks,
Alex.

#88

ukrbmw wrote:

I would get them full tread if you want them to last longer. They are molded to 6/32 and don’t have the tread squirm of a full tread RA1 that is molded to 8/32.

#89

If performance is not an issue then I agree you should go with unshaved. They will probably last twice as long before cording. When you start squeezing the last few tenths out of your lap times, think about shaved. Until you’re at that point, I’ll be surprised if you even notice a difference.

#90

Ok. I’ll get the full thread. I also agree. seriously doubt that I will tell any diff between shaved and full depth.

#91

ukrbmw wrote:

I’ve driven both in the dry and the full treads feel suprisingly good. Plenty of grip.

#92

Great. Thanks Simon. I found a pretty good deal - $590 shipped to my door for 4 tires.

#93

While we have yet to run a full season on R888 for the E30, we’ve noticed on our spec Boxster with shaved that the tires heat-cycle out around 25-28 sessions and get into their prime much faster. Interestingly they’re just about toast on rubber as well. When we run full-tread they take a few more heat-cycles to get into their prime but also heat-cycle out faster. Granted a totally different size tire and totally different car. :slight_smile:

Both shaved/un-shaved to generally gain about 4-6 PSI from cold to hot and the R888 are fairly predictable in that manner.

We look forward to this season and seeing what pressures everyone else is running and what the dynamics are with the spec E30!

#94

dgorman wrote:

[quote]
Both shaved/un-shaved to generally gain about 4-6 PSI from cold to hot and the R888 are fairly predictable in that manner.[/quote]

Don’t take this the wrong way but you aren’t driving the tires hard enough if they are only gaining 4-6 psi. Which probably also explains how you can get 25-28 heat cycles on a shaved set. It is interesting that you find the full tread heat cycle out quicker. I have never ran a set of R888 from full to cord so I have no experience there. Certainly something to keep an eye on.

#95

Not taken the wrong way at all! Really interesting points.

What have you noticed for normal PSI increases? (granted track temp/ambient temp variables) Also, do you suspect that with shorter and taller tires that it might affect overall PSI increases ? Are more people running full depth for the E30’s ?

We’re really excited to get new tire data on our E30 starting in March as I know Kenny (business partner and brother) will bust my chops about the data. It works out anyway since I crew for him when he drives the spec Boxster as I will need to bust his chops more and have him push harder (based on the data of course :slight_smile: )

#96

dgorman wrote:

[quote]Not taken the wrong way at all! Really interesting points.

What have you noticed for normal PSI increases? (granted track temp/ambient temp variables) Also, do you suspect that with shorter and taller tires that it might affect overall PSI increases ? Are more people running full depth for the E30’s ?
[/quote]

My left front shaved RA1 increases 11psi.

#97

dgorman wrote:

[quote]What have you noticed for normal PSI increases?
[/quote]

Off the top of my head I’m seeing around 8-10 psi depending on corner, track etc.

dgorman wrote:

Interesting thought. I have no experience with lower profie tires as I always run a 15 inch rim. My gut says it might make a small difference but really I have no idea.

dgorman wrote:

Absolutely run them shaved for racing.

dgorman wrote:

[quote]
We’re really excited to get new tire data on our E30)[/quote]

Certainly share what you discover.

#98

dgorman wrote:

I’m in line with the other guys. 10-12 lbs depending on the corner of the car.

dgorman wrote:

My uneducated guess would be that the size of the contact patch and volume of air inside the tire would dictate the increase in pressure. Assuming both tires are working as hard as they can, a wide, low-profile tire should see a bigger increase in pressure than our should-have-been-whitewalls high profile tires.

Steve D.

#99

I am the ‘other’ Gorman. A couple more notes…

We shave our tires because they are faster right from the get-go. If we don’t shave them, we end up getting them to their prime around 8-10 H/C and then we H/C them out before we run all the tread off. So lots of time (and slow laps) are wasted getting the tires to the sweet spot. When we shave them, we get about 25-30 H/C’s before they are toast. We generally have some rubber left and they are not corded at that point.

I just grabbed our tire data sheets. We generally see an increase in PSI of about 8-9 PSI from cold to hot. It’s true we may not be driving them hard enough, but we did set a track record in our car at Thunderhill for our class. I am sure it will be erased this year, I am just posting this so it’s clear it’s not like we are a back-marker.

In our car anything above 38 PSI was like marbles. We target 36/37 PSI. Different car, perhaps different deal. The sizes we run are;

Front: 225x45x17
Rear: 255x40x17

I am with Dan, it’s going to be a blast running the e30 and seeing the differences.

#100

Steve D wrote:

[quote]dgorman wrote:

I’m in line with the other guys. 10-12 lbs depending on the corner of the car.

dgorman wrote:

My uneducated guess would be that the size of the contact patch and volume of air inside the tire would dictate the increase in pressure. Assuming both tires are working as hard as they can, a wide, low-profile tire should see a bigger increase in pressure than our should-have-been-whitewalls high profile tires.
Steve D.[/quote]

In terms of heat the wheel and tire probably have to be treated as a system. A nasty one with lots of hard-to-predict variables. Easier to just pick a preferred wheel design and gather enough data that you can predict the tire’s pressure changes.

I would submit that brakes have a significant impact on tire temps. So much so that small differences in tire dimensions might not matter much. In this context, I’d suggest that the brakes don’t care what size tire you are running, except that one rim design might allow better cooling then another. But what might matter is that apparently the R888 doesn’t like large slip angles, so as our driving styles adjust to that the tire might end up a little cooler.