Martin S.

I have had some recent bad history with these tires, a blowout/failure in a high speed corner at 130 mph, did several 360s....didn't hit anyone or anything, pure luck. I am thinking maybe I cut a tire...it wouldn't just fail, would it? After all, lots of the club racers in my Club win with these tires on 2500 Lb cars..mine (97 Carrera) is 3205 Lbs.

Our Club tire support guy told me two things:
1. The 710 is very difficult to mount,
2. They don't work on heavier cars..they'll fail. He said the Camaro guys hated them...

Now with one of the four Kumho 710 tires shot, I was then in the market for a replacement tire. At $300 or so for a new replacement tire, I wasn't to happy. But then, I see an ad on E Bay, 3 used 710 tires for sale, in my size with 2 heat cycles, from a racing buddy no less...I run down and snap them up....then mount one of them up on the rear to replace the blown tire. Note he too blew a rear 710 on a 3200 Lb. 996 car, at Cal Speedway no less, very close to where my tire failed.

Off to the track I go this past weekend. About 3 laps into a qualifier, where one wants to push the car hard, I hear a thumping and I think:
1. I have lost wheel weight, or,
2. Maybe a wheel bearing is failing.
It couldn't be a tire failure, after all they were properly mounted and inflated to correct pressures, 27 front and 26 rear. Hot, I'f get them up to 36 Lbs. I didn't use a pyrometer.

Off the track I come...take the tires to the AIM Thunderhill tire shop for scrutiny. As it turns out, one of the rear tires has a substantial bubble in it, probably getting ready for a full de-lamination...not on my watch. So I switch out the tire with one of my remaining eBay tires...now the "wheels" are starting to turn in my head.

Off to the race, 15 laps on a 3 mile track. About 12 laps in, that damn thumping starts again and I am thinking, lost a weight....or??? I nurse the car around for the remaining 3 laps....looked at them at impound, they looked OK as far as inflation...didn't have a flat.

I will spinn up the tires again, just before I take them off and throw them in the trash. In asking around, I have discovered several people who in turn know other people who have had this problem with the 710 tire.

Me? I am going back to Hoosiers...Kumho 710, or any Kumho tires for that matter, is now persona non grata in my garage. As George Bush tried to say in the past, "Screw me once, shame on you, screw me twice, shame on me."

996FLT6

Damn that's bad luck. I never had an issue with kuhmo's other then tires rotating on rim which Hoosiers do as well. Now u just changed one tire with one of the used ones or replaced 2 in rear? Same tread thickness? Did u do proper breakin of the kuhmos(curing) ie drive it hard for 30 minutes then dismount? Also u may had a bad batch as well. Mike

Flying Finn

Here's my experience with those tires. I used one set of V710s in my car. 245/35 & 285/30 sizes.

Brand new, couple of days (IIRC 8 25-30 min sessions) in Sebring and they were great, did my best lap time at Sebring (high 2.26) and was happy as hell with them. Good grip and very balanced.

Then few weeks later went to Moroso and had practically no grip... It was kinda fun to slide around but I'd say my lap times were probably 3-5 seconds slower then normal (didn't time, just how it felt), before the last session took a close look and noticed a couple of blisters on one rear tire, one big chunk of outer layer missing and one smaller. Packed my stuff and drove home gingerly.

Even though they had great initial grip, I wouldn't but them again for the longevity (or lack thereof) but also seeing the blisters was rather surprising and not good.

Martin S.

Is the proof is the performance??? This is from the SCCA National...data from the Hoosier Web page, with citation of the SCCA link.

I don't see Kumho tires on the list...this has got to make you wonder, at least it makes me wonder....all I know is, tire blisters are unacceptable.

My Kumho 710 tires had been heat cycled, run for 30 minutes and allowed to cool for 24 hours. The used tire I put on had 2 heat cycles on it. Was it the used one the one that just bubbled? Be that as it may, I have lost confidence in these tires....and I am not the only one.


Total wins for the tire companies this weekend…………
1st 2nd 3rd
Hoosier 17 18 16
Goodyear 7 6 8
Avon 1
Michelin 1 1
Dunlop
Toyo 1 1 1
BFG 1 2 1

996FLT6

Kuhmos work best at 31 hot. Nething higher then 34 I'm sliding everywhere. But the way it sounds I woulda jumped ship as well. Mike

garrett376

Hey Martino - on my 3150lb off track weight 996 they were great... for 1 day of racing at Cal Speedway then they got progressively slower after that. I ran 34psi hot front and rear (35 in the right rear for Cal Speedway) and the wear was perfect, as was the tire roll-over. These were not previously heat cycled - just run right away. By the 18th heat cycle for our last Cal Speedway race, they had plenty of tread front and rear but where shot from a traction standpoint. I was into the ABS on braking and sliding through in every turn at Cal Speedway when I never had that problem before. They were nice for a day, but I won't buy them again as they fade a bit after 4-6 cycles, for cycles 7-17 they are still stickier than Nittos/Toyo RA1's, then by 18 cycles they are equal to chunked and corded Toyos despite having significant tread left.

Do you have LSD Martin? If not could you be spinning a tire for a prolonged period like a dragster, burning them up?

Martin S.

I do have LSD on my car....I have heard too many complaints, mine included. I just don't think they are up to the task, IMHO, of course. The LSD friction plates may be gone; I'll check that.

I am going back to Hoosiers....will be 100% Hoosier after I burn up my 18" Nitto NT-01 tires that I bought for Thunder Hill rain tires, and a set of Hankook Z-214s that already have 8 heat cycles.

dacbap

I had a set and ran hot temps of 25 f and 26 r (recommendation of local shop and he was spot on) if I ran them any higher psi they were slippery, they were great, I have heavy 996TT cabrio with strong mods both engine and suspension, I did notice they lost grip after first hard track day and considerably worst each session there after - only lasted 3 track days of 4 sessions each - but gripped like a mother! Looking for another alternative? BTW mine weren't heat cycled.

Martin S.

"Off to the race, 15 laps on a 3 mile track. About 12 laps in, that damn thumping starts again and I am thinking, lost a weight....or??? I nurse the car around for the remaining 3 laps....looked at them at impound, they looked OK as far as inflation...didn't have a flat."

A week after the race, I inspected the thumper. There was a huge bubble on the tread, and the tire was coming apart on the interface between the outside sidewall and they tread.

These tires do indeed suck for 3,200 Lb cars. They may work for 2,500 Lb cars, but for my car, and my buddy's 996, we both have had failures...me multiple failures, and they were properly inflated.

The remaining 710s are going into the garbage.

wanna911

I am on my second set of Kumho V710's, IMO they are GREAT. I got 24 heat cycles out of the first set while having a bump steer issue that blew slicks within two sessions. They held up to 4 days like that until I got it fixed, and then lasted some more, still running about 1.5 seconds slower and they still haven't corded yet. That set is kept as an emergency set in my garage now. I will however say that I run short sessions (usually 15 minutes), but my laps are not slow by any means.

I ran the first set at 36-38 PSI hot with no traction issues.

My second set, which are on the car now I had a better feel for the grip, and out of the box they have TREMENDOUS grip, but after 2 sessions they fall off by about 1 sec IMO unless you lower the pressures, then you can get a few more fast sessions, but they fall off a cliff. But at the same PSI they will last for 18-20+ heat cycles. Some of you are probably getting short life because you are running the PSI far too low. Hoosier warns against this as well. These are not full slicks, tire pressures should be higher.

I have only run Road Atlanta and Barber on them, and while both are easy on tire wear, both are also very hard on sidewalls with lots of compression.

My car (up until this week ) was 3300-3400 lbs race weight, and the weight was not an issue.

Camber 3.3 - 3.5 front, 2.8-3.0 rear.


You guys should check your setups for compatibility, pull out a pyrometer.

TrackDays247.com

V710s are known for being un-tempremental and easygoing. I've used them for 6 years.