Anyone here tired these yet??

How is the grip? DRY? WET? Sidewall stiffness?

I currently have Ecsta MX and thinking about XS these days..

Falken seems a bit of a hype to me some times..(maybe I'm wrong)

but ...

Some quote from SCCA forum

"Quote "Re: Kumho>Bridgestone?
Reply Quote
Sorry for the delay in response as there's too much fun stuff to do in Vegas and little time to be in front of a computer.

According to Rick Brennan, a 205/50-15 Kumho XS will be available as the only 15" size. Another size that may work for the EF Civic is a 215/45-16. I believe a 225/50-16 will also be made. There will be many sizes available in 17s and 18s as expected.

I spoke to a chief engineer and he tells me that the Falken RT-615 was the benchmark and that their test driver is consistently faster on the Kumho. Internally the tire has been known as the FK (Falken Killer). The test driver has also been faster on the new Kumho over the Bridgestone RE-01R.

If you're wondering why the one of the circumferential grooves is closer to the outside, it is for better rain performance without sacrificing dry grip.

Construction and design is finalized. Compound has yet to be finalized should be in orderly fashion to meet the April deadline. Cannot say whether all the sizes will be immediately available but time will tell.

Prices should be similar to Falken RT-615 prices which will represent a good deal for such a fast tire. "Quote"


http://sccaforums.com/forums/2/271367/ShowThread.aspx
SCCA forum

http://forums.nasioc.com/forums/show...php?p=23798742
WRX forum


what should I do...??

I'm thinking of 275/35/18 all around..

 

get the xs

 

I'm getting into autoxing next year and plan to use the Kumho XS tires. I just hate no one on this forum thus far has had any experience with them.

 

yes... lately my350z hasn't been that much informative compare to when I joined..

I guess, real deal ppl move up to GTRs and EVO X.....

 

I have autocrossed my Z on MX's, 615's, BFG KD's, (old school, not the KDW's) and now XS's (rear) and the star specs (front). When I bought the fronts, the XS's were not available in the size I wanted. A week later, the XS's were available in the size I run on the rear, and I got a set just in time for state.

Like the MX's, the XS's get better with heat, but the XS's start with more grip and get better from there. The sidewalls are not as floppy as the MX's but not as stiff as the 615's. I think they are just right.

I have not tried them in the wet.


XS > 615.

 

There is no national "street tire" class for the Z. So "national level" Z drivers don't bother with street tires.

This year, at the Florida State Autocross Championship, they offered an STU2 class, and I jumped at the chance to compete on street tires. The class had a good turnout and I hope the SCCA noticed.

https://my350z.com/forum/autocross-r...lass-last.html

 

I'm using the XS's now.

I upgraded from 225/45/17 MX's on all 4 corners to 275/35/18 on all 4 corners.

It's hard to compare them since the XS's are nearly 2 inches wider per tire. I obviously have LOADS more grip, the wheel doesn't "walk" back to center when it's unwinding like it did with the MX's, so I'm guessing the sidewall is stiffer.

The tire "talks" to you pretty well at the limit, but it's pretty quiet for the most part. I have a little bit of vibration (rumbling) from the tread blocks at speeds under 15mph or so, but don't notice anything at normal driving speeds. They definitely get better once warmed up, but they are still better than anything you NEED for the street even when at normal temps.

Road driving... I live in the mountains. You think Deal's Gap is good? I can show you better. I've been to Deal's Gap multiple times, sometimes on accident because I happen to end up in the area on my mountain drives. That being said, these tires are stupid sticky for road driving. Nobody needs this much grip for backroads. I can take corners SO fast that if there happened to be a stopped car around one of the many blind corners I would be totally screwed. I can enter a corner I'm unfamiliar with and have the wrong line for, turn the wheel, push the brakes, and they almost never even squeel. Definitely don't slide. But, I'm running 275's on all 4 corners. Your mileage may vary. A friend of mine has a Lotus Elise with RE-01R's (215 front, 245 rear), I was able to keep up with him on 90% of a VERY tight backroad. He also has track experience.

Track driving. I've been to VIR Full Course with these tires vs. my previous setup and the only difference was the tries, no suspension mods. It behaved the same as with the MX's, but I was going a lot faster. My self timing clocked me at 2:27 seconds and I felt VERY VERY consistent during that session. It took me a couple of sessions to get used to my increased pace, but it felt like a better version of my old MX's. They definitely hold the heat as long as you don't have them squeeling around every corner. I got the front tires a little greasy from trying to outdrive them a couple times. I just slowed it down to my safe pace and they were back to sticky a couple turns later. Very predictable in high speed corners (100mph+ up the Uphill S's and probably about the same through Horse Shoe). As long as you don't drive stupid and overheat the tires, they can take anything you throw at them.

They handle great in the rain. I have never had a pucker factor moment so far. I've used them down to 24 degree temps and they are like rocks until they warm up. I can roll on the gas in 2nd gear and light them up when they are really cold.

I highly approve of them. I would really like to compare them to some of the current tires regarded as being the BEST. Like the RE-01R, Direzza, and whatever else is popular. I haven't done a lot of tire research because the MX's were recommended to me by the vast majority of people I track with so I just got them and didn't ask questions. Then this last time I went to buy them again and found out they were on backorder and probably being discontinued so I went with their replacement the XS since I was happy with the MX's.

Like I said though, take this with a pinch of salt because I went from 225's to 275's so the grip comparison is weak since the added rubber skews the results. Overall I am stoked with the tires and would absolutely buy them again.

 

Sounds like a winner. Thanks for the insight Beau.
It will be some time ... but, when I buy my set I'll give a review also.

 

I 'd say go Falken

 

for what reason should I?


the MX rear lasted me 15000miles. which is same as stock re040s..

I want the threadwear to be like MXs..

will XS and 615 both suit my need?

 

I'm thinking about getting these when my stockers are worn out...

Anyone else have experience with these?

 

I really want to get the XS but sizes are very limited, even in 18s. They don't even have 255/40, 275/40/ or 285/40.

Also to those who has experienced them, do they tend to run wider than advertised?

 

this wasn't part of the topic but another tire to consider in the "extreme" performance class is the Dunlop Direzza Z1 Star Spec. I haven't seen the Kumho XS in action yet but for roughly the same price the Star Specs offer proven performance. The early XS reviews have been positive but its still kinda too early too tell.

My good friend w/ an S2k, who was consistly running AutoX laps 0.5+ seconds slower than me, replaced his Bridgestone RE-01Rs with Star Specs and was suddenly running 0.1 to 0.2 seconds faster in the season's last few events.

I'm looking forward to trying the Star Specs on my Z. They'll be my tire of choice next season.

TireRack.com seems to think pretty highly of them too.

The pro drivers of Best Motoring probably agree too.

 

^
Star Specs are very good tires, and I have a friend that runs them on his S2k too (I wonder if we have the same friend...lol). We went to Buttonwillow a month ago and he said they were really grippy.

I'm also disappointed that they also don't make the sizes that I want in 18s.

 

As far as I kno he's never driven Buttonwillow before but he's done Thunderhill w/ me. His name is Todd.

 

^
Okay different friend then. The winner of that race in that BM video had the new Bridgestone RE11s. To my knowledge they are only available in Japan for now but are the RE-01Rs replacements so the US should get them soon. Those will be the almighty street tires to beat.

 

Agreed. Those will probably be the new hot shyt when they come out.

As the video shows tho, the Star Spec still held its own with the best lap time of the day.

Also, I found it interesting that the best lap time of the day for the Star Spec came toward the end (lap 13 of 15) whereas the RE11 posted its best lap in the first few laps and appeared to become progressively slower.