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).