General R-compound question

Nikon FM

Is de-lamination common? What I mean is the bonding of the outer tread to the lower layers of the tire. I had a ~4" diameter, ~1/4 inch thick layer piece missing off my tire after my last track session. The edges of this missing area are easily peeled back away from the lower layer as well. It appears that the glue or bonding between the layers just failed.

The tire is at Les-Schwab (local tire shop) for their analysis or else I would have posted some pictures.

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Buddy Revell: "One man's sooner is another man's later"

SE

Hey Nikon,

Delamination that I've seen on race tires is commonly found when the tire has been overheated, used outside of their operating temp (too hot or run while too cold), or the psi was too low. What kind of tires are you using and for what purpose?

Nikon FM

Toyo R888 on the track (Pacific Raceways). Toyo recommends filling the tires to 35 PSI cold and then running them. After a bit of hunting on Toyo's site I found their recommendation on pressures and followed it.

I do like the tires and they have worked quite well for me so far this season.

__________________

Buddy Revell: "One man's sooner is another man's later"

Mike

seems kind of high, you could get upwards of 45 hot if you are running them hard, which it sounds like you are because they delaminated. I shoot for 35 hot on my track tires.

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NISSAN: 75 280Z / 86 300ZX GLL /87 Sentra SE / 03 350Z / 23 Z
Porsche: 93 968 / 23 Macan GTS / 93 968

Nikon FM

^ after further searching:
PROXES R888 | Toyo Tires

I found different information previously than what the link is showing. Kind of funny but the wear marks are perfectly at the top of the wear indicators when I filled 35 PSI cold and then ran on the track. Fairly solid traction with a touch higher pressure as well.

Hmmm….. now the guessing/estimating the best PSI before running begins.

__________________

Buddy Revell: "One man's sooner is another man's later"

BGTV8

You need to use a tyre pyrometer to check tread temps. Longacre do an infrared pyro although the probe type pyro gauge is substantailly more accurate. Delamination (or chunking in which whole tread blocks are thrown/torn from the tyre carcase) is univerally the result of an overheated tyre.

You are looking for a temp difference of 4-8 deg C inner to middle to outside of tread (inner temp of - say- 75 Degc, Mid-tread of 70 and outside of 65) would be a good temp as a conseqeunce of a 5-6 lap "run". A longer run at which the tyre reaches a stable temp, running the car at 10/10th, you might see temps around 85 degC after 20 or 30 minutes of 10/10ths driving. At temps above this, the tread will start turning to porridge and delamination will occur (as the rubber overheats, its chemical composition changes and "porridge" is the result, with rubber torn off by the road surface).

Infrared temp guns are not as accurate as a probe, but a lot more convenient.

With the tyre sizes used on a Zed, I'd be starting at 32psi and not expecting a hot pressure to rise by more than 6-7 psi max. If the pressure rises more, I suspect that the tyre compound ould be too soft for the application. Bear in mind that asphalt composition can have a marked influence on tyre temps and pressure build-up.

Are you aware of the R888 compound you used ... if it is the "soft", then the next set need to be the next grade "harder" - if "medium" you need to go to "hard", for instance.

RB