well one of them is. anyone who is running the ecsta V700's on the track please post your experiences. here's mine:

had a set of new unshaved unheat cycled ecsta v700's mounted before the expo and didn't use them at the expo. put them on when i got home and drove around for about 20 minutes to get a quick heat cycle in them. drove to gingerman (140 miles) on friday night for another heat cycle.

did 5 20 minutes sessions spaced evenly appart at gingerman. weather was in the 60's and sunny. started the pressures at 35 all around. after session one the fronts were at 45 and the rears were at 40. i asked a few people about these hot pressures and everyone said they seemed fine. second session hot pressues were the same. after my third session AUSMITH used a pyrometer on both front tires and the temps were even across both ties, same as before 45 front 40 rear. after talking a bit and seeing some slight rolling i upped the hot pressures by 2 all the way around. i did not check the temps after runs 4 and 5. but i would not expect the temps to be all that much differnt.

when i changed tires at the end of the day i noticed that the left front tire had significantly more wear than the right. a little bit is to be expected since most turns at gingerman are right handers but not this much of a difference.
[img]C:\Documents[/img]


upon closer inspection i noticed in a few area patches of tire had just ripped out



and the groove in the tread which goes around the circumfrence of the tire on the outer 1/3 of the tire seems to be ripping open.


right front is in much better condition


and the rears look great and wore evenly


i don't feel that at any point of the day i was over driving the tires/car and both AUSMITH and sackdz came with me and neither indicated anything to the effect of me overdriving the car (ed actually had me push harder).

it's also worth noting that dropspeed had the same issue with the front left tire ripping apart (to a much greater extent) after his fourth session. he swapped front to rear and had it happened to the new front left after his fifth session.

any opinions? overdriving? pressures to high? not heat cycled properly? these tires just plain wear like ***?

i am going to call tire rack and see what they say.

lance ~ who's going back to street tires


Modified by lanceh at 1:03 AM 4/21/2003

 

there was a post just like this in the RR/AX forum recently. Alot of the ECHC guys have had this problem. Theres a v700 sitting in my friends shop that looks exactly the same as that as well. Sorry I don't have naything to contribute about the wear problem. Try finding the post in the road race forum though.

 

Kumho, as well as other R compound tire manufacturers all reccomend that tires to be used for dry track racing be shaved to 3-4/32s. With full tread, there is too much rubber, and the heat build-up causes overheating that leads to the condition of your tires.

 

that could explain my problem but unless i'm mistaken dropspeed's were shaved.

 

I'm gonna say it's from insufficient heat cycling. Driving on them down the highway won't do much since they're not anywhere near up to temp. Figure 8's in a parking lot works better, then remove from car overnight. I wasn't able to heat treat my new RA-1s before the track, and they got greasy as hell as you know... but no chunking like that.

 

they look like they blistered.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jaker &raquo;</TD></TR><TR><TD CLASS="quote">Kumho, as well as other R compound tire manufacturers all reccomend that tires to be used for dry track racing be shaved to 3-4/32s. With full tread, there is too much rubber, and the heat build-up causes overheating that leads to the condition of your tires.</TD></TR></TABLE>

whoa never knew that... go to know... thanks.

 

Those are pretty high psi rates that u were running. I run at about 38/35 psi hot at the track and havent had any problems what so ever. I attribute that to a proper heat cycling procedure which extends the life of the tire.
Kumho recommends a hot psi range between 35-40. As a general gauge, a lighter car will use a lower psi.
U used a tire pyrometer...probe or surface...what were the numbers? Kumho recommend temps between 160 to 200 F.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 743 &raquo;</TD></TR><TR><TD CLASS="quote">there was a post just like this in the RR/AX forum recently. Alot of the ECHC guys have had this problem.</TD></TR></TABLE>

That stumps me. I'm on my 3rd and 4th set of those things. I beat the hell out of them, and have gotten perfect wear out of every set. No blistering, no uneven wear, etc.

 

I would say the pressures are pretty high, also. These things, for road racing purposes, seem to respond best with 27ish cold, 38ish hot.

 

I definitely feel there is a recent issue with quality Control at either Kumho or TireRack. I will be contacting both shortly. After using these tires for a year and a half with no issues, my brand new set of Shaved and Heat-Cycled Ecstas wore very differently at the first ECHC Race weekend at CMP. Here's what my driver front looked like... the rubber actually seperated from the cords.

ADD .orig.jpg on the end of that link to see the BIGGER PICTURE.
BTW.. Let me know what they say when you call them.
Also, Please let me know what size tire this was... I had 225/45/15. And I used the following cold pressures:
PR - 27
DR - 28
PF - 29
DF - 30
of course these will be slightly different at each track.

 

Are these the "newer" Kumho R-compound tires?

Didn't Kumho admit that there was a quality control issues w/ the newer R-compoung tire models? (Is Victoracer the newer model? Sorry, don't know all the names of Kumho tires.)

 

Ecsta V700 is the 'new' Kumho R compound, Victoracers are the 'older' tire they have made for some time.

Pictures don't do it justice. The front left looked horrible compared to the other three. Chunks, rips, everything.

Chris - who thinks Lance should return to burninating the Azenis and thatched roof cottages.