THSCC Forums

I recently got a great deal on some track wheels w/ tires. The tires are Kumho V700s with one autox on them. 3 of the tires look great, but one has a chunk on it. Please look at these pics of it.. do you think this tire is toast or can i run on it or fix it somehow?

http://www.goldteamrules.com/chunk1.jpg
http://www.goldteamrules.com/chunk2.jpg

It seems almost small.. is there a way to patch it up w/ something? Would it be pretty dangerous to autox on? what about a HPDE?

Thanks

That "chunk" looks to me like cord. The tires may have had one autocross on them, but it must have been a hard one.


Me thinks it is toast and I would look at the other 3 to see if they lived particularly hard lives and are one brake lock-up from cording too. Else you may end up buying 1 tire p/month for the next 4 months and having 4 tires in various states of wear.

Just my opinion, I have been known to be wrong once

Since I'm not a tech inspector, I can't speak authoratitively on this, but the tires should be fine for auto-x with the missing chunk.

One thing to check for, however - were those tires shaved before the current owner started using them? Conventional wisdom on that tire says you really _have_ to shave them for proper wear unless you plan to run them full tread depth as a rain tire. That chunking could be overheating, which can happen with the Escta V700 if they're not shaved. The Escta can also have an artifically short life when they develop the "groove of death" - check the SCCAforums for more detail.

A friend had some chunking issues on track even with shaved Escta V700s. In his instance, the chunking was on the outside tread block. A Kumho rep advised him to flip the tire on the rim and continue to run them. I know that they made it through one additional track school after that.

I'm making that tire sound worse than it really is - I have a new shaved set ready to go on my car for the season up here in MD. If cared for properly, they are good R-compounds for the money.

_________________
Tom Freeman
'98 M3/4/5 | '93 Spec3 325i | '12 TSX sport wagon | '03 Tahoe
Team Silver Bullets '91 240SX

hrm thanks guys. looks like i need atleast one more person to chime in

the tires were shaven to 4/32nds and heat cycled by Tire Rack.

I'd send it back to Kumho and ask for my money back. Or Tire Rack. That's just not acceptable.

I'd toss it. No sense in taking the risk for a $120 tire.

_________________
Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

If you can get them to warranty a competition tire that fails because what is most likely a lack of negative camber, skip going to the negoiating class I told you about and start teaching it!

_________________
Rich
http://www.v8mongrel.com/

I don't see any other indications of overheating or chunking anywhere else on the tire. And the other 3 are fine. The shoulders even look fine. The failure looks like it started at ONE spot on one tire. Looks like a defect to me, or localized "trauma".

Can't hurt to try for a replacement. Get someone good on the phone and offer to send the pictures and/or the tire back to TireRack or Kumho. Ask lots of questions about whether this is normal. See what happens.

_________________
Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

Mike, first thing:

That's me. I have (kinda, sorta I thought) been there, done this.
Second, you are correct, that is not over heating or edge chipping which is what I had. Mine was caused by a high center of gravity, heavy front weight bias, no camber gain and life on the left front at Roebling. In essence, lethal injection for a tire. So, I haven't really been there done this as my situation it was clear that something beyond the tire construction caused the problem.

The tire shown, if all I had was a closeup of the problem, I would have sworn was a circa 1995 Comp T/A R1 with a bad case of evil-groove-of-doom. While not common, if you totally missed on your tire pressure guess with fresh rubber, you could 'spot cord' (aka chunk) right by the central grooves. In this case, from the shots provided, the wear pattern of the tire is not consistent with that. It could be that the use duration of one autocross is not enough to establish an overall wear pattern and this one tire was just pushed beyond its limits while on an incorrect pessure level and this is the result. However, without a clear indication of abuse like mine, Mike is right that you should pursue this with Kumho. Your personal ethical standards will dictate whether or not you tell them you didn't buy the tires new.

FWIW, you could be SOL no matter what. If these tires were bought on closeout by the original owner, like mine were, they are the last of the older, more fragile compound of Ecsta V700. Tire Rack sold them out warning everyone of this and Kumho cannot replace it; they would have to give you four of the new tires, which, it would seem to me at least, more of an uphill negotiation.

While you are on the phone with Kumho tech, they can give you some excellent advice on these tires. Pressures, temps, how to heat cycle them, etc.

_________________
Rich
http://www.v8mongrel.com/

I am not sure what you guys are smoking...these tires have been through a lot more than 1 autox. It might be my eyes, but it appears that there is a serious concrete scuff mark where the missing tread is.

These tires were abused. Yes, you can probably run them at an autox, if tech does not see the cord. Otherwise, figure you just got a good deal on some wheels.

_________________
Jim Pastorius
2008 Silverado VortecMax
1992 Camaro CMC#92
2002 BMW R1150R

2009 3rd Place CMC Mid-Atlantic Championship
2009 CMC Hyperfest Winner

yeh it is odd. the other 3 tires look great. but this tire alone looks just beat up on more so than the others. The guy who sold them to me said he had a 300hp turbo'd GTI, got these tires, ran an event, and then wrecked the GTI and sold it. who knows. i guess heavy + high HP + FWD can be a little rough on a tire

i think i'll just go w/ it and see what happens for autox. id be driving to the even on street wheels/tires of course so ill have a spare on hand if needed.

Hmmm, maybe he wrecked the car with these tires on it??

Bret.

Dan:

Courious, did you send the tire back to Kuhmo, what did they say?

Also, I have to comment: if you think a tire is not safe to autocross
at say speeds from 30 to 50mph, then why would you think it safe
for a HPDE when speeds will be double that (100+) with tires
loaded for longer periods of time in high speed sweepers?

_________________
Mark Vitacco
THSCC TT Chairman
mvitacco@bellsouth.net

maybe he was asking in case it was safe for autox, but not hpde

no, i didnt take it up w/ tirerack since i didnt buy them and essentially got the tires for free w/ the wheels. plus i think itll be ok for autox.

i don't plan to run a HPDE on them. the next one i plan on attending is in Nov so then ill either buy one or two new tires (if they hold up well) or scrap em (if they dont)..