Who is running on Kumho Ecstra MX?
 

Who is running these? looking for a good street tire that will only see summers as the car only sees summers, and one that will give decent results at an autocross or a rx7 meet in the twisties.

Also what is the difference between a max performance tire? and a ultra high performance tire? (as per tirerack)

I'm looking at the specs at the tirerack ratings pages for these tires:


225/50/16
Sp8000
712s
Kum Mx
RE730 Gen II

they all have similar rankings, but how can a UHP have similar thread life as a max performance tire (ie sp8000 vs MX)

FYI, "Max Performance" is a subcategory of Ultra High Performance, Tire Rack made up .

Ultra High Performance is the Rubber Manuafacturer's of America's accepted performance tire category for tires designed for extremely high performance applications (ie for cars with very high performance potentials).

Tire Rack tries to compare tires objectively, but 30-second autocross courses just don't tell you enough about a tire's performance.

For one thing 30 second courses just don't heat the tires enough for maximum grip. The best way to test a tire's ulimate performance is to track test at high speed road courses.

This stands to reason because UHP tires come with closed end speed ratings of 168 mph (W) or 186 mph (Y). Some come with the old open ended speed rating of Z (140 mph or faster).

30-second autocross courses give you speeds of up to maybe 55 mph. Not really high enough to understand what the tire's capable of.

Until I see REAL track test data gathered with telemetry from the same car with the same driver, Tire Rack's tests results are merely a very rough guide. IOW, I wouldn't put much weight in Tire Rack's test results.

Read a tire comparo done by Grassroots Motorsports or Porsche Club of America's Panorama. The Pano, in particular does an excellent job comparing R-compound tires. The results showed conclusively that the Michelin Pilot Sport Cup Comps outperformed Kumho Ecsta V700 and Pirelli P-Zero Corsas. The tests were done on the same car, Porsche 996 Carrera. The same tire sizes were used. The same driver tested the tires. The test was done at the same road course in one day.

The MX is a new Kumho tire, and has not been in the market long enough for any of us FD owners to try them. The general consensus for the replacement tire of choice for FD Rx7 is the Bridgestone Potenza S-03 Pole Position.

I'm running Kumho Ecsta MX's on my FC in 225/45/17 and 255/40/17, in the front and rear respectively. I've had them for about 100 miles so it's hard to tell how the tread wear is, but so far I am very impressed by the tire. They seem more responsive than my old setup, but then again, it's hard to compare these to my old 205/55/16 Firestone Firehawks for several reasons. One, being that I bought the car w/ these on them and they were almost bald, and two, the dimensions of the tires are very different. But the MX's are definately a big improvement. I will be going to my first autocross with them in about two weeks, so I will let you know how it goes.

Hey, you gotta sidewall pic? I was thinking about running the MX's also, are they a stiff sidewall like the 712's?(shitty tire) or are they a rounder sidewall??