Contact Patch: Kumho Ecsta MX and Ecsta V700

For many autocrossers, road racers and track driving enthusiasts, the name "Kumho" indicates just one tire, the Victoracer V700 R-compound DOT-legal competition tire. That's about to change. Not only does the Victoracer have a new, even stickier stablemate, Kumho now makes a street tire that fulfills the high expectations the brand set for itself on the track. "Ecsta" is Kumho's name for its ultra-high-performance street tire line, launched in 1999 with the Ecsta Supra 712. That tire has been very successful, helping increase Kumho's UHP market share from 0.4- to 10% in 2 years, but hardcore driving enthusiasts have often been less than inspired by its performance. Kumho's objective for the new Ecsta MX was to bring affordability to the high-image summer tire market segment. In pure lap times and handling characteristics on the cars provided for us, the Ecsta MX is on par with some of the best maximum-performance street tires.

Founded in 1960, Kumho is the world's tenth-largest tire manufacturer and also the youngest in that group. It manufactures tires for everything from heavy equipment to aircraft, hitting a lot of high-performance and pure racing cars in between. Kumho USA was founded 1980 as a commodity-tire importer and reseller. It is now the fastest growing tire company in the U.S., with sales growing from $126M in 1997 to projections of more than $300M in 2002. Kumho's grassroots racing involvement began in 1991 with the Victoracer V700, which now holds 30% of the DOT-legal race tire market.

The Ecsta MX is Kumho's highest-technology product. Kumho aimed the Ecsta MX at maximum performance in dry and wet conditions. Compared to the Ecsta Supra 712, Kumho indicates the Ecsta MX achieves a 25% increase in dry grip, about 20% better dry handling and about a 5% gain in wet handling. It makes tradeoffs in comfort, wear and noise characteristics. Developed in the U.S. at Kumho's Akron technical center with the experience from the Victoracer V700, the Ecsta MX's E Grip tread compound features a new additive to extend the upper limit of its operating temperature range. ESCOT is Kumho's term for its computer modeling technology, used to optimize the contact-patch contour for improved steering response and pressure distribution, and to maintain casing shape at high speed.

A jointless cap ply gives high-speed durability; the Ecsta MX carries a Y speed rating (186 mph). A multi-radius tread profile maximizes contact area and pressure distribution under hard cornering, giving increased lateral grip and predictability at the limit. The directional tread pattern features large center grooves to evacuate water, allowing the lateral grooves to be smaller. The resulting larger tread blocks give smaller slip angles with increased grip and stability under cornering. A new bead profile provides improved tire-to-wheel fit and better uniformity, as well as better protecting wheels from curbing.

european car drove the Ecsta MX back-to-back against the Michelin Pilot Sport and the BFGoodrich g-Force T/A KD on The Tire Rack's standard test course at its new facility in South Bend, Ind. The cars were The Tire Rack's three Lexus IS300s--not European, but not all bad, either. They were fitted with Eibach Pro-Kit springs, but were otherwise stock automatics, said to be identical. All the cars understeered at the limit; lift-throttle response was smoothed by their transmissions, and the tail didn't step out easily or far. Lap times were taken, as well as segment times around a constant-radius turn, enabling lateral acceleration to be determined. The test was repeated in the wet. The best and average times and lateral accelerations achieved by the journalists present are presented in a table (see below).

In the dry, the Pilot Sports understeered heavily, hurting their times. This was a characteristic of the tires on this particular car; our experience shows their handling is nearly perfect on some cars for which they are original equipment. The g-Force T/A KD had the most grip, but the steering didn't feel as good. The Ecsta MXs were clearly the best suited to the IS300s. They felt the most natural on the car, with good steering feel and front-to-rear cornering balance.

In the wet, the Kumhos put power down in a straight line better than the BFGs. Breakaway under cornering was easier to control and happened at a higher speed. The BFGs' steering feel improved in the wet, but they didn't get the power down as well and went slower on the constant-cornering portion of the course. The Michelins were better balanced than in the dry, with less understeer, but still didn't turn in as well as the other two. They seemed to have the best grip overall. I was unable to spin the rears while exiting the constant-cornering section onto a short straight, but with the Kumhos and BFGs, I could use power to drift the tail through that section.

Driving on the road, the Ecsta MX was somewhat noisy, with tread-pattern rumble on the new, smooth pavement at and around The Tire Rack. It was nothing like a Yokohama A032R, but the sound was still noticeable on the quiet, smooth hatchback we drove. On the other hand, the Ecsta MX provided good grip for reasonable street driving. Some of the freeway pavement was grooved across the road and made the quietest tire howl.

We can't report on durability yet, as our experience was limited to one day, and the cars were driven only a minute at a time, not long enough to cause blistering or chunking from heat buildup. Just by looking at the Kumho's aggressive tread pattern with its large blocks, though, we predict they will withstand harder-than-average use quite well.

The Ecsta V700 is Kumho's new DOT-legal competition tire. The Victoracer V700 will continue to be supplied, giving racers a choice if they find the new tire is not to their liking. The Ecsta V700 has a new casing profile, new compound technology, lighter weight construction and a symmetric, directional tread pattern. It will be supplied in 15- to 18-in. sizes, priced roughly 20- to 30% below its primary competition. The Ecsta V700 is somewhat stickier than the Victoracer, and may prove more delicate, perhaps less durable. Kumho instructed that it must be shaved and heat cycled prior to track use to avoid blistering. european car drove the Ecsta V700 on a four-cylinder BMW Z3, provided and track-prepped by Track Time driving school. With only two runs of two laps of the 30-sec. course in a new car, it was difficult to get a clear impression of the tire, except to say that grip was definitely present. The cars were lighter but less powerful, and lap times were about the same as the IS300s.

Kumho has proven its ability to build a great tire in a very demanding arena: racing. Now, it is upping the ante in racing and getting serious about building street tires. european car is impressed so far and is looking forward to more experience with both of these tires.

Things We Liked
·Grip
·Handling
·Price
·Appearance


Things We Didn't Like
·Noise


Things We Don't Know Yet
·Durability


Competitors
·BFGoodrich g-Force T/A KD
·Bridgestone Potenza S-03
·Continental ContiSportContact2
·Dunlop SP Sport 9000
·Michelin Pilot Sport
·Pirelli P Zero
·Toyo T1-S
·Yokohama AVS Sport.


Other Stuff
·220 UTQG
·Y-speed rated (186 mph)
·Available in 23, 15- to 19-in. sizes

Kumho Tire USA
14605 Miller Ave.
Fontana, CA 92336
(800) HI KUMHO
Fax: (909) 428-3994
www.kumhotireusa.com


The Tire Rack
7101 Vorden Parkway
(800) 445-0179
(574) 287-2316
Fax: (574) 236-7700
www.tirerack.com