Kumhos

[ek1]

After suffering compound delamination on my front tires AGAIN a day and a half into my 2-day track weekend at the Glen, I got too excited after seeing some ad for a Kumho tire rebates on Tire Rack. After reading their web site, of course the ACR tires are not eligible

Out of despair, I started reading reviews of a regular (non-ACR specific) Ecsta V720. And guess what? Out of 32 reviews, literally every other one states that these tires are delaminating during autocross/track driving. Some people also experienced blistering and chunking (and so did I). Check it out: https://www.tirerack.com/tires/tires...RatingsReviews

So frustrating......$700 in tires per weekend. And that's taking it easy. I think my fastest lap there was 1.23.xx and I made it a point not to drive for more than 20 min per session and 4 sessions per day.

I've had it. I'm putting Hoosiers on the front for the next track event.

[ACRSNK]

Damn...that can get expensive.

[DZnutz]

Have you contacted Kumho with photos and details?

[ek1]

Have you contacted Kumho with photos and details?

Why? It's not like they are going to keep replacing my tires for free. I already read several reviews that said they contacted Kumho about these tires falling apart and got zero results.

[sadil]

Damn, that is nuts. What kind of wear do you expect on the Hoosier's? What is "benchmark" wear for driving 9/10ths to 10/10ths.

[ACRucrazy]

After suffering compound delamination on my front tires AGAIN a day and a half into my 2-day track weekend at the Glen, I got too excited after seeing some ad for a Kumho tire rebates on Tire Rack. After reading their web site, of course the ACR tires are not eligible

Out of despair, I started reading reviews of a regular (non-ACR specific) Ecsta V720. And guess what? Out of 32 reviews, literally every other one states that these tires are delaminating during autocross/track driving. Some people also experienced blistering and chunking (and so did I). Check it out: https://www.tirerack.com/tires/tires...RatingsReviews

So frustrating......$700 in tires per weekend. And that's taking it easy. I think my fastest lap there was 1.23.xx and I made it a point not to drive for more than 20 min per session and 4 sessions per day.

I've had it. I'm putting Hoosiers on the front for the next track event.

Dodge/Mopar was just running a buy 3 get 4th tire free deal. The Kumhos at the dealer qualified I believe.

[Rare Snake]

Dodge/Mopar was just running a buy 3 get 4th tire free deal. The Kumhos at the dealer qualified I believe.

I don't know if it's different in the U.S. but up here it only applies up to 18" tires I believe. In all honesty, that's not even that great of a deal.

[IndyRon]

I don't know if it's different in the U.S. but up here it only applies up to 18" tires I believe. In all honesty, that's not even that great of a deal.

If the 4th tire free is a Rear one, its a very good deal.

[Rare Snake]

If the 4th tire free is a Rear one, its a very good deal.

Very true LOL

[ek1]

Damn, that is nuts. What kind of wear do you expect on the Hoosier's? What is "benchmark" wear for driving 9/10ths to 10/10ths.

At this point the only thing I expect from Hoosiers is not to be worse than Kumhos, which is - I want to be able to get more than 2 track days out of them. Of course, if it rains, my track day will be mostly over since Hoosiers and standing water dont mix.

I dont know what the benchmark wear is for driving 9/10ths or 10/10ths. I think some forum members here do that and they can chime in, but I remember reading posts that mirror my experience - 1-2 track days max out of set of fronts. I personally always drive at 7/10ths since I dont want to run out of talent.

[DZnutz]

Why? It's not like they are going to keep replacing my tires for free. I already read several reviews that said they contacted Kumho about these tires falling apart and got zero results.

Seems like the most logical course of action. I dont care what someone, somewhere on some online thread posts. I would go to the source and get a resolution. Some people simply like to complain but not really accomplish anything

[ek1]

I agree with you, but I already have a full time job and a family, so at this point my time is more valuable than spending days on the phone with someone at Kumho, trying to convince them that their tires are shit. They already know, but will never admit it because if they do, they will incur multi-million dollar losses from having to replace delaminating tires. So I won't complain. I'll just vote with my wallet and use another brand of tires.

The goal of my post was just a warning to anyone who is considering an ACR-E as a track car.

[sadil]

I agree with you, but I already have a full time job and a family, so at this point my time is more valuable than spending days on the phone with someone at Kumho, trying to convince them that their tires are shit. They already know, but will never admit it because if they do, they will incur multi-million dollar losses from having to replace delaminating tires. So I won't complain. I'll just vote with my wallet and use another brand of tires.

The goal of my post was just a warning to anyone who is considering an ACR-E as a track car.

Thanks for the input. I totally agree. At this point, the Kumho tire being chewed up on the track quickly is well documented. For ACR owners, the first set will really determine if your going to be using the tire throughout the life of the car. Looking forward to seeing your impressions after switching to the Hoosier. I still would love to have one rear tire to hang in the garage that says "ACR". I think that's super cool!

[RedTanRT/10]

ek1, saw this thread and the other you posted. Those factory Kuhmo's seem like a great qualifying tire to set lap records for a street tire, but all I ever see and read is that their track life is ridiculously short.

I've run Hoosiers on my G3, G4 and now Comp Coupe and never have seen these type of issues. Viper front's wear twice as fast as the rear's, but I've never seen Hoosiers come apart like this.

IMO, if your gonna track a G5 ACR, go with an 18 set up all around and run with A7's or R7's. Keep the Kumho's for the street

[Dman]

Isn't there an 18" wheel option out now for tire options?

Now that I'm in an ACR, and starting events, this is going to be an issue for me, no question.

[ek1]

ek1, saw this thread and the other you posted. Those factory Kuhmo's seem like a great qualifying tire to set lap records for a street tire, but all I ever see and read is that their track life is ridiculously short.

I've run Hoosiers on my G3, G4 and now Comp Coupe and never have seen these type of issues. Viper front's wear twice as fast as the rear's, but I've never seen Hoosiers come apart like this.

IMO, if your gonna track a G5 ACR, go with an 18 set up all around and run with A7's or R7's. Keep the Kumho's for the street

I am afraid of running 18's because of so little clearance between the caliper and the rim. Even with my stock wheels, my calipers have scratches from shit stuck between them and the rim. Plus, believe it or not, I _STILL_ have the original rear tires from the factory mounted on the car and they are still good for a few more track days at least. So it's just the front tires that are a problem.

I already bought a set of stock 19" front rims and mounted 295/30/19 R7s on them last year, just did not get a chance to use them. But now since I am already doing another wheel alignment, I'll put them on. I will be creating a separate thread for recommended height/camber/pressure settings for them.

[RedTanRT/10]

Isn't there an 18" wheel option out now for tire options?

Now that I'm in an ACR, and starting events, this is going to be an issue for me, no question.

Dman, I see a guy from LA at Dan Cragin's shop that has a CCW 18 set up. Might be other choices too? Seems like there are thread's on this board discussing.

But, as ek1 points out, seems like with 18's there is a very tight clearance and folks get concerned about about wayward rocks/pebbles getting lodged between the wheel and caliper

[ek1]

Isn't there an 18" wheel option out now for tire options?

Now that I'm in an ACR, and starting events, this is going to be an issue for me, no question.

There are several options out there (I have all those threads bookmarked, will post later tonight), but clearance between the ACR CCB caliper and the 18" rim is literally a few millimeters. If a hard object were to jam itself in there at high speed....well...who knows what will happen, but one thing for sure - it will be expensive as hell to fix. From what I recall, there are also tire rubbing issues at full compression with some configurations. That's why I have been holding off on 18's. It's also a one-way street in a way that you can't just take 18's off and throw stock wheels back on without redoing the wheel alignment, which is again....expensive. Then there is corner balancing that has to be redone (expensive).

Good luck with tracking your ACR. You are not going to believe how much fun it is. But open your wallet really, REALLY wide.

[PkB2014]

What's the point in 18" all around since A7/R7 come in stock G5 sizes already? Seems unnecessary. I was planning to just get another set of wheels in stock sizes and put some Hoosiers on them for when I want do AutoX or Track days.

Also, the Demon tires (NT05r) doesn't come in 18" for the viper but does come in stock wheel sizes. If someone were interested in drag radials.

[ek1]

What's the point in 18" all around since A7/R7 come in stock G5 sizes already? Seems unnecessary. I was planning to just get another set of wheels in stock sizes and put some Hoosiers on them for when I want do AutoX or Track days.

Also, the Demon tires (NT05r) doesn't come in 18" for the viper but does come in stock wheel sizes. If someone were interested in drag radials.

We are taking about ACR tires and stock rear for the ACR is 355/30/19. As far as I know, Hoosier does not make R7 or A7 in that size. Tire Rack now has Pirelli pZero Corsa in 355/30/19 for a small price of $640 _PER_TIRE. Fok that!

[PkB2014]

We are taking about ACR tires and stock rear for the ACR is 355/30/19. As far as I know, Hoosier does not make R7 or A7 in that size. Tire Rack now has Pirelli pZero Corsa in 355/30/19 for a small price of $640 _PER_TIRE. Fok that!

A7/R7 come in 345/30ZR19. It fits.

If you want 355 then they make real slicks in that size. Cheaper than the Corsa too IIRC.

EDIT: I'm not a track pro by any means. I'm just interested in the reasoning behind the suggested setups compared with the research I have done myself.

[Snorman]

FWIW...this is very common knowledge. And it's limited to the fronts. The rears were just fine but the fronts don't last more than a day (or two). They are, however, relatively inexpensive compared to tires I've ran on other cars so I'm okay with it. $320/tire is relatively cheap for a track tire with the capabilities of the Kumho.
But yeah, I wish they were a little more durable. Suspect it is due to the very short sidewall.
S.

[ACR Steve]

"I think my fastest lap there was 1.23.xx " that would explain it . You would be faster then an Indy car at the Glen long Course..............I think your times are off

Go with the R7 or A7 at the track . They will survive well

[ek1]

"I think my fastest lap there was 1.23.xx " that would explain it . You would be faster then an Indy car at the Glen long Course..............I think your times are off

Go with the R7 or A7 at the track . They will survive well

Finally, someone is paying attention!

I looked at the video again and the time is correct, except in that session we were running the Nascar configuration:
glen nascar config.jpg

The full course time was 2:04:810
Glen full course.jpg

[stradman]

FWIW...this is very common knowledge. And it's limited to the fronts. The rears were just fine but the fronts don't last more than a day (or two). They are, however, relatively inexpensive compared to tires I've ran on other cars so I'm okay with it. $320/tire is relatively cheap for a track tire with the capabilities of the Kumho.
But yeah, I wish they were a little more durable. Suspect it is due to the very short sidewall.
S.

^^^ This. I have 2 sets of wheels and tires. And lots of front spare tires. I am expecting to get 1- 1/2 days max per front set of tires if I am caning the car. It is what it is. I don't understand why it seems you are so angry about this. Sure it would be great if you could get 5-6 days out of our tires, however when you are tracking a high downforce, heavy, front engined car and going really fast and generating a lot of G's something has to go. And in this case its the fronts. Its a simple as that. Its physics. I'm very sorry to say this and I'm sure you won't be happy in my saying this, but if you want to play with an ACR then you have to pay. Please don't take it personally either. Alternatively if you want to go with slicks then trailer the car, although that comes with other issues and ....costs