Help diagnose race tire wear pattern

Chuck Moreland · 08-21-2002, 10:09 AM

These pictures are of Kumho V700 ECSTA DOTR tires. These are the successor to the Victoracer. I have some strange wear patterns and would like some feedback on potential diagnosis.

The background -

I used them on the rear this past weekend for two days at Streets of Willow. We ran the track in opposite directions on the seperate days so the wear would have been averaged out.

It was very hot. Ambient temps ran around 100-106F! I don't know what the track surface temp was but you can bet it was smokin.

I also did not measure tire temps. Wish I had now.

I ran the rears 36 psi hot.

The tires have not been shaved. These new V700 Ecsta have a bit more tread depth than the older Victoracors, I think an extra 1/32 or 2.

The passenger side tire was relatively new. It now has about 6 track days on it. It had normal, even wear pattern before this weekend. You can see a strange wear pattern. A ridge formed about 2 inches in from the outside edge of the tire, the tire wore flat from the ridge to the edge. The wear is very uniform however is a bit rough at the ridge.

The driver side tire has normal wear. This tire has more days on it as evidenced by the lack of tread. Probably had 10 days before this event.

So what do you think is going on here?

My conclusion is the tire got too hot and was chunking off. Had the tire been shaved, this probably wouldn't have happened. Or if I had run a higher pressure it might not have happened.

The driver side was already worn, in effect it was shaved on the track. Hence the problem didn't happen to the driver side.

Alternate explanations please.

One thing I have learned is to ALLWAYS measure tires temps. The data can be invaluable. Had I done this I probably could have avoided this problem and even if not, I'd have some usable information for diagnosis.

StuttgartDavid · 08-21-2002, 01:24 PM

Are you sure that the ridge isn't a build up of molten rubber from the track and your/other's tires?

Chuck Miller · 08-21-2002, 01:40 PM

Very interesting Chuck,

I ran my new Ecstas last June at the 'Streets' for the first time … after getting 5 track days from my Victor Racers.
My ware pattern was similar but the ruff ridge is about another inch in (tapered from the center deeply towards the first circumference tread line) I was given some BAD (read low) inflation info for my first practice and got them very hot ( checking hot pressures ...unfortunately no pyrometer) After the first practice I was more intuitive and ran them like the Victors (mine like to be about 36lbs. hot as well) They seem to work though… ran my best time on my last lap, and bettered my best time for the track… 1:19.1
I would have been on the track with you last weekend but I drove the car up to Monterey for the Historics. In anticipation I already mounted the Estas 'inside out'. Will probably see you at the next event in Sept. … we can compare notes.

Chuck Miller .. Metallic Blues 73' -S H-Production

john_colasante · 08-21-2002, 02:01 PM

I would guess underinflation caused the outside edge to wear unevenly. You're right, a pyrometer would've shown this.

sammyg2 · 08-21-2002, 02:41 PM

I haven't run the new V700s but my victoracers likes more pressure than 36 hot. On a 911 I would probably run 34 cold and let them hit around 40 to 42 hot. Anyone have any experience with both tires?
LEGAL DISCLAIMER:
This is just my gut feeling of what worked for me, I am no expert :-)

scca_ita · 08-21-2002, 03:39 PM

In the past under inflated BGs would do the same thing. But they where really fast that way.

36PSI hot is not that much PSI I usually go out with about 33 - 35 PSI cold.

Chuck Moreland · 08-21-2002, 04:26 PM

Thanks for the input. I think I was underinflated for the conditions.

Again a pyrometer would have answered all.

74911s · 74911s's Garage

i ran my v700's at 26/30 hot this weekend.

i found running these tires with less air dramatically improves the grip and i have not experienced the same symtoms as chuck.

interesting to follow...

Emission · Emission's Garage

Was the suspect tire brand-new, or had it been heat cycled before? All tires 'cure' one they run through a heat cycle. If you subjected that tire to track temps without a heat cycle, I am sure you would see some strange wear (or chunking).

Two weeks ago, I drove my 2002 VW Passat to Phoenix with ambient temps 105-113 F. in the desert. After the five hour drive, my all-season Michelins were reading 140-145 F. on the tread surface (via infrared thermometer)! Hot asphalt, combined with high ambient temps will make for some hot tires. I can only imagine how hot YOUR tires got!