New Tire Choice - Kumho ECSTA XS

[ACRBruce]

I spoke to Kumho at SEMA last month about they latest performance tires, the ECSTA XS which was designed for SCCA racing and high performance driving in mind. Even though the wear rating is a high 180 but was told the rating was used to make the tire eligible to run in certain street class events with the SCCA. I did my finger nail test and the tire seemed to be almost as soft as the V700 that I run in my Lotus with a 50 rating, and softer than the NT01 Nitto's with a 100 rating. They are suppose to heat up in no time so they would be perfect for our cars for the street AND they even have 345/30-19's. Fronts are 315/30-18's so will they fit Gen III and IV's? But I suspect these tires will get greasy a lot sooner than the PSC's so these may be perfect for the street and autox while the PSC good for the big track. Here's a link to Kumho's site for more information:
Kumho Tire USA - Passenger - Ultra High Performance - KU36

Has anyone tried these tires yet?

 

[Leslie]

wow you must have been reading my mind.

I have run the Kumho Ecsta MX's on the track for the last 4 yrs (5 sets so far) and have loved them...Needed tires last month and they were OUT everywhere, so I went with the Nitto 555RII's...100 tread wear rating...well ONE wknd at MID Ohio and my front left is GONE hahaa.

I am very excited to hear Kumho has come out with a new roadrace tire, I will be all over that one real quick!

 

[Viper X]

Hey Bruce,

I'm a big fan of the Kumho Ecsta V700s. They stick very well and wear pretty well. I wish they made them in a 345 x 30 or 35 x 18.

I doubt that the new XS will be as robust or sticky, but hope so.

I am anxious to hear your feedback on them though.

Also, too bad they don't make it in a 305 x 18 as that's a good fit for the front of a Viper. With the 315 x 18, you will (in your SRT-10) need to be very careful with wheel offset, ride height and spring rate as this size tire extends past the outer fender lip, even with 2.5 negative camber.

And the rear 345 x 19 tire is super heavy at 37 lbs. Much heavier than a 345 x 30 or 35 x 18 tire. The 19 inch wheel will be heavy too, heavier than an 18 inch of the same width.

Not sure who's making these decisions at Kumho, but they should ask us what we want before they go making new tires in our relatively rare sizes.

Dan

 

[Early93Viper]

I would love to have them compared to Kumho V700s by someone who has tracked there car on both. I have used Kumho V700s for 3 years now on the track and off and think there the best tire money can buy. Especially on the track where there just amazing and last forever compared to other track tires. Now if they can make a tire that will do all that and doesn't sand blast my sidesills that would be epic.

 

[ACRBruce]

I agree 100% on the V700's, I've been running a set on my turbocharged Lotus (same HP to weight ratio as a GenIII) and the rears are only 1/2 worn, fronts are 1/3 worn. And do they stick. I was running Yoko AO48's and I was able to break them lose at will in first gear but not with the V700's. But many V700 sizes have been discontinued and you really have to check around for availability. When the Tirerack doesn't list them, still check around though as they don't always carry all the sizes.
When I was talking to the Kumho rep about the ECSTA XS, I was under the impression that more sizes will be available so I'm hoping 285 or 295 18's will come out soon. And yes 315-18's might be too wide for the OEM fronts also other than rubbing issues. Since these tires will not be expensive as compared to the PSC's, and used OEM 18/19 wheels are fairly cheap, these might just make a very economical second set of wheels/tires.

 

[adg44]

Awesome, glad to see that another manufacturer is making tires in our size. I will use one of my contacts at tirerack to see if they can get pricing on these yet.

One thing I noticed was that they say they are "Y" speed rated (186 MPH), but all the specs listed show "W" (168 MPH). Hopefully that is just a typo.

- Anthony

 

[SFYellow]

I spoke to Kumho at SEMA last month about they latest performance tires, the ECSTA XS which was designed for SCCA racing and high performance driving in mind. Even though the wear rating is a high 180 but was told the rating was used to make the tire eligible to run in certain street class events with the SCCA. I did my finger nail test and the tire seemed to be almost as soft as the V700 that I run in my Lotus with a 50 rating, and softer than the NT01 Nitto's with a 100 rating. They are suppose to heat up in no time so they would be perfect for our cars for the street AND they even have 345/30-19's. Fronts are 315/30-18's so will they fit Gen III and IV's? But I suspect these tires will get greasy a lot sooner than the PSC's so these may be perfect for the street and autox while the PSC good for the big track. Here's a link to Kumho's site for more information:
Kumho Tire USA - Passenger - Ultra High Performance - KU36

Has anyone tried these tires yet?

Any idea when these tires will be available from tirerack or any other tire retail stores?

 

[ACRBruce]

The Tirerack doesn't always carry all the sizes so it'd be great if other forum vendors to chime in on availability.

 

[Grant]

Last a checked a month ago, Kumho was planning on doing a production run of their larger size tires in "3 to 4 months", according to the supplier on the other end of a phone at Discount Tire.

On their website, Kumho claims these tires have an optimum temperature of 205 degrees. Most street-touring (or ST, the SCCA solo class these sorts of tires are developed for) overheat pretty quickly after repeated lapping, so if they are telling the truth this is a good sign.

On my ****** car, I replaced a blown Dunlop Dirreza (an amazing tire, currently the fastest in ST) with a single Kumho XS. I can do some testing with them and report back, but I can say my durometer doesn't report them as being as soft as my Dirrezas (or of course real R-tires, like PS Cups or NT-01s).

 

[j-rho]

The scoop I got on these tires from a Kumho-sponsored autocrosser, who tests cars for a living, is these tires are on par with the other current ST tires Grant mentioned (Yokohama Advan Neova, Bridgestone Potenza RE01R, Dunlop Direzza, Toyo T1R), with better-than-average heat handling capability. Unfortunately I don't think any of the ST tires listed come in Viper sizes so a direct comparison isn't likely to be too valid.

I would guess they end up being similar in performance to the C1-spec Michelin PS2's available on 2008 Vipers (not Sport Cups).

 

[adg44]

Here is the deal on these tires from Tirerack:

Fronts (275/35/18) are in stock now and retail price is $242/ea.

Rears (345/30/19) are due in February and retail price is $399/ea.

If you're interested in ordering, talk to Alex at Tirerack and he'll take care of you.

- Anthony

 

[ACRBruce]

Here is the deal on these tires from Tirerack:

Fronts are in stock now and retail price is $242/ea.

Rears are due in February and retail price is $399/ea.

If you're interested in ordering, talk to Alex at Tirerack and he'll take care of you.

- Anthony

Anthony,
When you say the fronts, which size were you referring to? 315? Hope the 295's will be available soon.

 

[adg44]

Anthony,
When you say the fronts, which size were you referring to? 315? Hope the 295's will be available soon.

Sorry, when I say fronts I mean 275/35/18's.

- Anthony

 

[ACRBruce]

Finally, I mean after two and a half years, I finally broke down and got those XS tires. Forget those 295 fronts, this is time to go wider so I ordered wider 18x11 fronts for the 315/30-18 tires and I'm happy to report there's no rub whatsoever. Wheels are Forgelines from Partsrack who btw has customer service second to none. I debated for two years whether to go all black or gray on the wheels or to go bling, then I saw the Laguna Seca edition and thought maybe I will go half way and had the outers of the wheels painted red. The XS tires ride real nice and still quite sticky when cold, much better than the PSC's. Rears are the standard sized 345/30-19's.

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[FrgMstr]

Wow, awesome thread necro. Only took me two weeks or so for me to get'em on my Viper.

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[Barrels]

Love these tires. Got the rears off eBay and the fronts off tirerack. $1,100 shipped. Tue mag comparos I read all showed better laptimes with the xs than ps2's, but only in the dry. They aren't as predictable in the wet. I had them on a wet morning at VIR with no complaints, but I was far from pushing it until the track dried up.

 

[02 Graphite GTS]

My only question for Bruce is what kind of rubber you planning to put on the baby stroller???

 

[ACRBruce]

My only question for Bruce is what kind of rubber you planning to put on the baby stroller???

Nothing but run-flats.