Thanks for your input (I swear I just read this post on the SCCA Forums IIRC)! Edit, nevermind, you posted this on a different tire conversation here.

My original post doesn't apply anymore, I just scored a set of 03-05 Track wheels with a set of Hoosiers!

 

yea ... i did post roughly the same thing in the wheel/tire forum. someone asked about the kumho xs vs. falken 615.

seems like the XS is generating alot of interest and their just isn't alot of reviews out there yet.

 

Looks like it will be a good tire, just crap sizes for 18" wheels.

 

I just checked TireRack.com. Looks like they have 225, 235, 245, 265, 275, and 315 available in 18's now. What more do you want?

 

+ 1.

The I had no problems with their selection of 18" sizes. I thought Kumho's size variety was just as good or better than some of their Extreme class tire competitors.

I've heard some people complaining that Kumho makes a 285/40/17 but no 285/35/18. Kumho certainly isn't alone in stopping at 275 for this class tho.

 

Not to hijack the thread but what is your opinions of the Nitto Invo? I have the NT555 now and think they are a great tire..wish I had something a little stickier so I looked into the R888 from TOYO. I was told they do not make them in my sizes...275 and 245 35-19..SO they suggested the Invo. I do not autox but do race the Big Bend Open Road Race. I want something stickier to help out of the hole should I need it. The nitto's are great tires but I really can't even mat the pedal until high into 3rd gear..and even then it will spin sometimes. 529whp....

Suggestions???

 

Beau how many miles do you have on the Kumho XS's. I was thinking of going 285/35-19 and 265/35-18 on my Nismo. My RE050's are getting worn down after 16,000 miles

 

I know you you were not asking me but I thought I would put in my .02 as I have ran a pair of the XS's down near the wear bars already.

The grip from these tires is the best of any tire I have ever ran. (They get better with heat too.)

The star specs are a little better "cold" than the XS's but the XS's get up to temp quick and then leave the star specs behind.

I can't speak to how well they wear because my use of these has been pretty extreme. (State Championships, two days of unlimited track time -lost count of all my runs in the 40's, a "test & tune" day, and another "points" event day.)

I don't think I have much more than 1k miles on the star spec / XS combo on my car, but they are both close to the wear bars. Now that I have the "unlimited" track days out of the way for a while, I hope to get 2, maybe 3 more points events out of the set.

 

Do you think they'll wear better than the stock Potenza RE050's on my Nismo?

 

My 05 Base came with RE040'S and they didn't hold up well when autocrossing. I have no experience with RE050's however, so I don't know.

I think the XS's held up better than the 615's, KD's, and RE040's would have though.

 

Proper diameters, such as a 275/40. Nearly all the 18" XS are too short for a street driven Z if you want to maintain stock diamater.

 

Listen i had these in 225 40 18 -- 255/35/18 in my Lexus they bubble to hell with the potholes sidewalls suck ***. Its a crappy tire.. Stay away from Sumitomo and Kumho's

I would look into Pirelli P Nero Zero i finally paid for some good tires and these last me about 4 years of abuse on that car... I've played cheap with tires in the past and it has cost me thousands trust me do it right the first time around

 

I was able to find some less that or equal to 2.1% of original size there.

http://www.miata.net/garage/tirecalc.html

 

Amen. I plan on buying the XS for dual purpose-street and track. I have VDC so it's more sensitive to wheel/tire diameter variances away from stock spec. If only they made 255/40/18, 275/40/18 or 285/40/18 I'd buy them right now.

 

You'd more then likely be fine putting the sizes that are only 2.1% shorter then stock, but I don't like putting artificle miles on my car...

 

What tire pressure would you recommend for stock tires (225-fr/245-r) to use on track? I usually raise it upto 42-44 PSI cold to have just about 47-49 PSI hot. Is it too much? I have not done a chalk test yet and I am not even sure it is that usefull. Any thoughts?

 

are you referring to drag track or circuit track?

at the circuit,
i usually put 35 in front and 33 or 32 at the rear.
you should put more in front to counter the understeer issue (considering you have stock suspensions and tyres setup).

 

Sorry, I meant circuit, not drag.
Interesting... 32-35 - is it really enough? Aren't you going to chew on sidewalls in higher G turns? How about steering response at lower pressures?

 

Since your in Seattle...Road course.

I haven't tracked the Z yet. However, I've tracked a 95 M3 Race car and 2004 SVT Focus that was setup for the track. 45 days between the two cars in the last 4 years.

At Pacific Raceways - Focus 215/40/17 Nitto NT-01 R-compounds - 33 f/31 r. That was due to the rear wing helped with the down force and the car wouldn't snap the rear around in T2.

I wouldn't adjust temps unless there was an hour in between sessions.

M3 245/40/17 Hoosier R6 - 32 Left side 34 Right side because of all the left turns at Pacific and the track is so rough in several areas, T8 and T2 with the different areas of the corner being patched through the years.

Opposite at Portland on the M3 31 right 33 left.

I can find out what two of my friends ran in their T2 Race car Zs at both tracks.

I always use a log book when I track and put down tire temps as it took several track days to get it dialed in, and outside temps noted in the book as well.

 

In two laps at Pacific your going to raise the psi easily by 8-10 PSI. This is why a lot of instructors at Pacific tell people to do two laps to get R-compounds up in heat then go more aggressive on the track.