Kumho V700 problems...

[Marsh]

Well I found a good reason to go back to the victoracers.

This is the inside and outside shoulders of my front left after a lapping day at Waterford Hills. There is still plenty of tread, but it wore through on the shoulder and it feels and sounds like it's starting to come appart.

Inside (still looking good): http://www.pimp-eng.com/images/lapping/P8050046.JPG

Outside: :( http://www.pimp-eng.com/images/lapping/P8050048.JPG

I can't get the Victoracers in my size this late in the year, so I've turned these around on the rims and will try to squeeze the last three regional slaloms out of them.

The straight line is amazing, but it doesn't seem to be worth the cornering woes. Maybe they would work better with a stiffer suspension, but suffice it to say they don't seem to be working well for me.

[tanney]

Marshall, according to Andrew at Wheel and Tire Zone, that wear is typical.

Mine looked just like that after the second Pro Solo this year. I guess they don't like doing 18 runs at 40 something degree ambient temperature in the parking lots we run in. I did the same thing, had they switched on the rims and all is good again.

Apperently these tires are experiencing very high failure rates, so just having excessive wear is a good thing.

[Moose]

By the look of them ... The V700's need lots of neg Camber ... 2.5 degree's +

[tanney]

Moose, I had heard before I even bought these tires that they DID NOT like stock camber.

I do believe that Marshall is running a fair bit of negative camber, but I am stock.

I bought them this year because, even though I had heard this, they were supposed to be faster than the Yokohamas, which now I am doubting.

[Moose]

The wear pattern suggest that the stiff sidewalls and lack of camber is causing them to run on the outer edge of tread / sidewall.


Marsh ... what sort of camber are you running and have you used a pyrometer to see what tire temps you are getting across the tire.
The fact that much of the wear appears to be right where the tread meets the side wall suggests to me that perhaps there is not enough tire pressure to support the carcass, thus there is more pressure on the side-wall / tread area ... wearing them prematurly.

Wes, with your total lack of camber, and the stiff side walls of the V700's, you are not maximising the contact patch ... thus not maximising grip of the softer compound ... so the Yoke 032R's with their softer sidewalls (but harder compound), will deflect enough to give you a bigger contact patch. This might explain why you feel that you might be getting better grip with them.

I would also guess that you have much more tuneing potential with the Yokes ... as tire pressure plays a much bigger role with the soft side-walls.


Cheers

TAO

[Marsh]

Originally posted by Moose
The wear pattern suggest that the stiff sidewalls and lack of camber is causing them to run on the outer edge of tread / sidewall.

Wes, with your total lack of camber, and the stiff side walls of the V700's, you are not maximising the contact patch ... thus not maximising grip of the softer compound ... so the Yoke 032R's with their softer sidewalls (but harder compound), will deflect enough to give you a bigger contact patch. This might explain why you feel that you might be getting better grip with them.

I would also guess that you have much more tuneing potential with the Yokes ... as tire pressure plays a much bigger role with the soft side-walls.


I'm running around -2.0 deg of camber up front. I don't have a camber kit, the car's just that low. At both Delaware and Waterford I'm getting 10-15 degrees hotter on the left side of the tread, both sides of the car, due to all right turns. The camber seems OK, but the body roll is too high. And yes it now appears that I'm not running enough air pressure. BTW the new V700 are the softest side wall competition tire I've ever seen. They don't feel much stiffer than my T1S street tires. Not like the Victoracers. Those had a enough side wall complience to be forgiving, but they would still work well with my soft setup and heavy car.

BTW my tire pressures that day were around 42-44 hot. I only checked them once, it was just a lapping day.

[ctenche]

I tried the new Ecsta V700 this past weekend at Shannonville and I wasn't too pleased with the feel of them. They seemed mushy to me with not as much initial bite as the old Victoracers. Like Marshal said, this is probably due to the softer sidewall.

I was running 42/38 hot. I took tire temps after one of my sessions (making sure to not slow down too much on my last lap) and noticed that the centre was significantly lower than the outside edges. This was on the front wheels. I upped the hot pressures to 48, went back out and took more temp readings when I came back in. Outside pressure were now just above 200º which is above Kumhos recommended temp but the centre was still lower. As a side note, the tires felt greasier and the sidewall did not seem much stiffer.

These things are weird. I didn't have this problem with the Victoracers or the RA1s.

I'm gonna give them one more try and if I can't sort it out they're gone.

[Moose]

2 degree of negative camber may not be enough you can get some adjustable ball-joint s for your car if memmory serves me ... .... most r-compounds (except the BFR R1) like 2.5 degrees plus .. I am currently running 2.8 degree's and my RA1's seem to like it .... pretty even tire temps across the tread.


Based on Caius response more tire pressure may be required ...

Cheers

Moose

[Marsh]

The adjustable ball joints (Dave had them) hit the strut tower. No something I really want to deal with. I think that -2 is plenty with a stiffer suspension (which I should have in a week), just not for these tires.

[Chris91GT]

I'm no expert, but the V700s on the Mustang have been great thus far. They grip far better than the A032Rs that I started the S1 season on, and after 4 events they are not really showing any wear yet (ok, so one event was soaking wet, but the other 3 were hot, hot, hot). All at Shannonville. I do, however, run -3 degrees camber and it works the entire width of the tire very evenly.

[Dave Barker]

I have the new Ecstas with the K8A ( read last years ) compound. I have not found them any faster than the Victoracers , actually a bit slower but this may have been due to the track being a bit slower for many at Shannonville last wkend so I'm not sure if it was the tires , me or the track. OTOH tire wear is not a problem. They will certainly last as long as last year's Vicotoracers ( which is not too suprising seeing as they are the same compound ) .

And yes I have neg 2.4 camber . The biggest wear issue is at the rear due to the zero camber of my live axle. Appropriate rotation seems to help.