Kumho V710 Problem, Tire Rack's Response

LeadSSled · Post by **LeadSSled** » Tue Jun 28, 2005 8:44 am

MarkP - I've not been able to locate the "Kumho complaint" thread on the SCCA forums yet. Still searching...

steverife · Post by **steverife** » Tue Jun 28, 2005 9:31 am

...it was something about V710's and loyalty. It turned into a flamefest because some American Sedan guy said they suck for his purposes.

If you want to take that route, start a new thread asking for better contact info/help. Be careful how you word things though, a few people on the site are very pro-Kumho and get defensive real quick. Most of these kinds of threads turn into flamefests.

LeadSSled · Post by **LeadSSled** » Tue Jun 28, 2005 9:35 am

not cbring wrote:Be careful how you word things though, a few people on the site are very pro-Kumho and get defensive real quick. Most of these kinds of threads turn into flamefests.

Thanks. Just for the record, I am not negative on Kumho (yet), I am pissed at the TireRack. It's quite apparent that they did not even consult with Kumho on this issue.

Mustangracer · Post by **Mustangracer** » Tue Jun 28, 2005 10:05 am

I never use Tire Rack to actually buy the tires, I just use their site for research. Fishcer Tire in Knoxville (3 locations) has a good selection and their prices are slightly more expensive than Tire Rack but the customer service is much better. They also give you an out-the-door price instead of having to buy the tires, wait for Tire Rack to ship them, take them to the shop, have the installed, etc. I dont know all the brands they carry but I lnow they have performance tires.

LeadSSled · Post by **LeadSSled** » Tue Jun 28, 2005 10:11 am

Mustangracer wrote:I never use Tire Rack to actually buy the tires, I just use their site for research. Fishcer Tire in Knoxville (3 locations) has a good selection and their prices are slightly more expensive than Tire Rack but the customer service is much better. They also give you an out-the-door price instead of having to buy the tires, wait for Tire Rack to ship them, take them to the shop, have the installed, etc. I dont know all the brands they carry but I lnow they have performance tires.

Randy - I've dealt with Fisher in Farragut since 1997 on all of my non-Kumho tires, and they mount my Kumhos for me. Great folks, but they are not a dealer for Kumhos.

MARKP · Post by **MARKP** » Tue Jun 28, 2005 10:35 am

I have also had a lot of luck with Matlock on Kingston Pike in Farragut. John Brown @ Ted Russell Ford Parkside has also helped several of us out.

The only places you can buy Kumho competition tires, that I am aware of, are Vilven and Tire Rack.

LeadSSled · Post by **LeadSSled** » Tue Jun 28, 2005 11:02 am

Well, I'm certainly not getting much sympathy at the SCCA Forums.

http://sccaforums.com/forums/141983/ShowPost.aspx

TedV · Post by **TedV** » Tue Jun 28, 2005 11:13 am

Terry,

The number for Vilven, is (217) 583-3277 and that’s all I got to say here on a forum

MARKP · Post by **MARKP** » Tue Jun 28, 2005 11:27 am

I think most of the replies on SCCA Forums are probably reasonable.

I took a look at the link to the pictures. I wonder if some of the most recent comment about tire pressures might be something to pursue. In the past, I have seen some tires cord in that same area due to a tire pressure issue. What can happen is the tire has a very strong corner but when underinflated, the corner will actually cause the tread area to buckle and wear 1/4 to 1/3 of the way in. This will cause overheating and cording in that area.

I can't believe Tire Rack suggests temp ranges above 200 degrees F for these tires. They would be mush at that temperature. The comments about the 710 needing to be almost cold are correct. Everyone that is fast on these tires at national events is keeping water on them after the first runs. That said, I doubt the issue you have has anything to do with a temperature in the 200-230 range.

The spot you show in the pictures seems a little odd. It's hard to say that is necessarily a blister. I have seen similar damage caused by debris on the track if you had the wheel locked and went across it, or if it was on a wheel that was accelerating across the debris. In my experience, if the tire blisters, it will do it in several spots in different areas on the tire. That's not to say that there isn't an issue with this particular tire but that there are other possibilities, too.

LeadSSled · Post by **LeadSSled** » Tue Jun 28, 2005 12:18 pm

It appears in my frustration and impatience, I've been a little hasty in my criticism of the Tire Rack. After a week's worth of e-mails and phone calls, I've just received some more relavent technical feedback from "Woody" (posted below). Amadeo, the customer service contact also offerred to sell me 2 new tires at half price to help ease the cost of replacing the blistered tire. This will allow me to have tires with the same number of heat cycles and the same diameter on the same axle. I'll order these already heat cycled from the Tire Rack to avoid that problem.

I am still VERY interested in feedback on how to prevent this problem from reoccurring. I'll order a pyrometer today. Any feedback on tire temp targets, air pressure, etc. will be greatly appreciated. Thanks to everyone for their valuable feedback.

Latest message from the Tirerack:

**************************************

I see Penny has authorized a discount on two replacement tires.

While he has been autocrossing first on street tires and then a used set of V700s
before these brand new V710s, there are several important things he must remember.

The more performance oriented the tire, the more fragile it can be. The V710 has
proven to be very fast, but also very sensitive to its first heat cycle. If not
properly heat cycled, the compound can be damaged for future use. If temperatures
are allowed to spike too high on the first hard use, permanent damage to the compound
can occur.

As an autocrosser for over 10 years myself, I agree with John that doing figure
8s in a parking lot is not a good or proper heat cycle, regardless of how much temperature
he feels by hand. I have tried it and it does not work. All it does is scrub the
very outside shoulder of the tire, possibly overworking that area, and under-working
the rest of the tire. A proper heat cycle builds temperature evenly and gradually.
Doing the figure 8s builds temperature in the shoulder very rapidly, and is localized
as mentioned above.

If he insists on heat cycling the tires himself, then a better way to do it is take
a highway drive for 30 minutes or so. He must resist the temptation to drive fast
around corners or off-ramps on his way to and from the expressway. If he doesn't,
it is the same as the figure 8s. Once the gentle drive at highway speed is completed,
the tires must be removed from the car, or the car jacked up so there is no weight
on the tires for at least 24 hours.

The used set of V700s he has used before, while faster and more fragile than the
ECSTA MX street tires, they are much more forgiving than the V710. Also, since they
were used when he purchased them, they already has some heat cycles on them, making
them more durable than the fresh V710s.

As another autocrosser's observation, in his original photos I see lots of wear
in the shoulder area. Without knowing more facts about his specific vehicle set
up and pressures, I suspect he may need more air in the front tires to help control
tire roll over, or some more tuning work to reduce the understeer. This much localized
wear indicates one or both of these. As he knows, the Impala SS is a heavy, powerful
car. Front tires will take a beating if care is not taken.

Woody -SCCA autocrosser since 1989

LeadSSled · Post by **LeadSSled** » Tue Jun 28, 2005 12:25 pm

MarkP - Based on the fact that I could hold my hand on the tires, the tire temps were more like 130 degrees. At least that how hot an injection mold (molded plastic) tool can be for me to be able to keep my hand on it here at work. The info page for the V710 says "210-240 degree" teperature range. maybe that's for road racing and not autocross, but it does not specifiy.

I am quite sure it is a blister. It was much more proniounced before I took it off of the front and put it on the rear. I noticed the problem after the 411 event and put it on the back to race at ORM on Sunday.

Thanks for everyone's feedback. If there is any advice on tire temps/pressure for this heavy car, I'm listening.

Post by **thrdeye** » Tue Jun 28, 2005 12:27 pm

Looks like what I did to my V700, but hard to tell since V710's have no tread. Try more air pressure.

MARKP · Post by **MARKP** » Tue Jun 28, 2005 12:28 pm

Good to see they took care of you on it. The only real way to get the proper air pressures is with a pyrometer. Some experienced drivers can do it based on wear and feel but the pyrometer is the best method. When you get one, get a "probe" type. The infared ones are convenient but the probe types are much more accurate for tire temps.

LeadSSled · Post by **LeadSSled** » Tue Jun 28, 2005 12:31 pm

MarkP - OK. Do you have a recommendation on temperature targets? I know the goal is to have them as even as possible across the whole tread, but what is the proper temperature range?

If you know of a (relatively) economical probe type device, you might save me some search time. Thanks

steverife · Post by **steverife** » Tue Jun 28, 2005 12:51 pm

I think TireRack did more than they had to do, just like they did when the replacement wheel they sent me was stolen. They also ship VERY fast. I am very happy with TireRack and will continue to buy from them whenever possible.