Kumho Ecsta XS (new tyre)

[nitroman]

These replace the former MX model in Kumho's lineup. They won the 6-tyre shootout in this month's Grass Roots Motorsports mag, beating (from closest competitor to backmarker) Bridgestone Potenza RE-11, Bridgestone Potenza RE-01R, Toyo Proxes R1R, Dunlop Direzza Sport Z1 Star Spec, & Falken Azenis RT-615. This same article mentioned that the old Kumho MX was a perenially bad tyre.

They have a great price as well, with 205/50R15 $91, and 215/45R16 $98 at The Tirerack.

[tigerdog]

Unfortunately, no 205/45s. Too bad this is such an odd size.

[tweetdriver63]

Unfortunately, no 205/45s. Too bad this is such an odd size.

True, but how much difference would running a 215/45 really make? The overall diameter of the tire is 10mm more, leaving only 5mm less space under the wheel wells, and making your actual speed would be 1.7% faster than indicated (Since your actual speed is probably about 10% slower than the speedo indicates on 205/45s, that would just make your speedometer a little more accurate). They would also stick out 5mm farther, not such a bad thing (would protect the rim a little, maybe) and the tread width in contact with the road would be 10mm more (better traction?).

Some might think the extra 5mm in sidewall height would be detrimental to handling, and I defer to anybody who's a racer, and knows more than I do about that, but it seems like a really small difference to me. I think that would be true when comparing the two sizes, in the same tire, but as different tires have different stiffness in the sidewalls, I would think that would have more impact on handling than a small difference in sidewall height. For normal driving, I don't think it would make that much difference, and it may also make for a smoother ride, having that extra 5mm of air to ride on.

[nitroman]

Unfortunately, no 205/45s. Too bad this is such an odd size.

True, but how much difference would running a 215/45 really make? The overall diameter of the tire is 10mm more, leaving only 5mm less space under the wheel wells, and making your actual speed would be 1.7% faster than indicated (Since your actual speed is probably about 10% slower than the speedo indicates on 205/45s, that would just make your speedometer a little more accurate). They would also stick out 5mm farther, not such a bad thing (would protect the rim a little, maybe) and the tread width in contact with the road would be 10mm more (better traction?).

Some might think the extra 5mm in sidewall height would be detrimental to handling, and I defer to anybody who's a racer, and knows more than I do about that, but it seems like a really small difference to me. I think that would be true when comparing the two sizes, in the same tire, but as different tires have different stiffness in the sidewalls, I would think that would have more impact on handling than a small difference in sidewall height. For normal driving, I don't think it would make that much difference, and it may also make for a smoother ride, having that extra 5mm of air to ride on.

215/45 is acceptable. It doesn't detract much from responsiveness, whilst 225/45 is a noticable change. Only thing... I used 215/45s with only 8/10s" of tread (not 1"), so there was less tread squirm.

[AutoXM100]

A close friend I race with switched to these from the Dunlop Direzza Star Spec after comparing prices and reading the same Grassroots article. He said they weren't anywhere near the grippiness of the Star Specs but he was very pleased for his money. He noted they were far better than his older Falken Azenis RT-615. These are mounted on a VW R32 Gti. I say go for it. They build up to heat quickly, have a great dry traction rating and are equivalent to the cost of most non-competetive tires.

As far as the size goes, I am currently running 215/45/16s and I wouldn't switch back if you paid me. I am considering a 225/50/16 in the future, solely to run Potenza RE-01Rs.