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Discussion Starter #1
I'm looking at a new set of tires for my 05 Mustang for autocross and some street driving. My last set was Kumho MX 275/40-17 on 17x9" wheels and they were pretty decent for a drive to the AX, compete and a drive home. Now I am considering the Dunlop Sport Z1 Star Spec and the Kumho XS as replacements for the older MX's.

I have experience with the Dunlop on my Toyota and they worked very well, but the largest sizes I can get are either 255/40-17 or a 275/35-18. I would prefer a 17" tire as they are much more affordable. In Kumho I can get a 275/40 or a 285/40 tire in 17" and at a good price point. I just don't know which would be the better AX tire, which is my major concern.

Has anyone tried a set of the Kumho XS yet in an autocross? Any comparisons to the Dunlop would be a plus. I appreciate any input I can get.
 

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Discussion Starter #3
Well, Tony, I think I am going to go with the Kumho XS in a 285/40-17 size unless someonoe can convince me otherwise. I just read a tire review by cgrant on cc.com and they seemed to work well for him at the Gainesville test track except for getting greasy after running several hot laps. Since hot laps aren't much of an issue in AX and you can cool the tires between runs they may be the ticket in the size range I want.

If Dunlop had the Z1 in a 275 or 285 18 incher I would be all over them, but they don't. I would also have to dismount my Cooper street tires to use my 18x9.5" wheels and still buy another set of 17" tires for my 17x9 wheels since the MX's are getting too thin for driving on a wet road.

The XS in 285 is under $800 for the set so I can't complain about price.
 

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For autocross, the Dunlops are proving to be faster. Giving up a little section width for a better compound shouldn't be a concern. Along those lines, the Bridgestone RE-11 is also around $200/ea for a 255/40-17 and is probably just as fast, if not faster. The Kumho XS seems to be good bang for the buck and would (I'm guessing) be a great all around tire, but they aren't proving to be the quickest of the current ST tires, by a pretty good margin. If you check sccaforums.com, there's a bunch of opinions on the current 140 tread wear contenders in the Street Touring section.

I think Grassroots Motorsports is going to have one of their tire shootouts this coming month, which should give good data. I think the test should also include the new Yoko AD08...that's kind of the problem with buying any of the current "hot" tires, there's a bunch of new ones coming out that will probably be faster :)
 

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I don't think my level of driving skill is gonna be enough to show a significant difference between the three that i'm looking at. I just wish I had more solid info on the NT-05's.

The Lotus and Miata using the XS's locally certainly parade them as a really stick tire, but there is also an STi laying down times .9 slower on the StarSpec's vs. the same size tire in a V710 Kumho.

I still have a month or two to decide before I really want to make a purchase. Id rather have some feedback from someone like you in a heavier car, though.
 

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Discussion Starter #6 (Edited)
A good friend of mine had a set of XS on his car and didn't care for them. He said they took a while to warm up and then got greasy pretty quick. He also had issues with then chunking out. I sort of take that with a grain of salt though since he has a Porsche GT2 and usually runs $400 tires on his expensive German cars.

I think I may check out SCCA Forums as Tigerdrvr suggested and see what is being said over there before ordering anything. I also have not checked on the sizes you can get the NT-05 in. I am a bit size conscious because my 05 is a Roush and it sits pretty low with the springs I have on it. I would like to keep the tire diameter as close to 27" as possible to avoid scraping up my front fascia (any more than I have already).
 

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I browsed SCCAforums first before making the initial thread here, but from what I can remember(since I ended up making the thread here), I was finding more small car testimonials like Honda/Miata/4cyl cars.

The StarSpec seemed to have more of a fan-base, but I attributed that to being on the market longer.

Nitto is showing a 275/40/18 that is nearly 27"

http://www.nittotire.com/#index.tire.nt05.sizes
 

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Discussion Starter #8
I browsed SCCAforums first before making the initial thread here, but from what I can remember(since I ended up making the thread here), I was finding more small car testimonials like Honda/Miata/4cyl cars.

The StarSpec seemed to have more of a fan-base, but I attributed that to being on the market longer.

Nitto is showing a 275/40/18 that is nearly 27"

http://www.nittotire.com/#index.tire.nt05.sizes
Yeah I like the Star Specs on my ST FX16 too, but a 255/40 is pretty short for a 05+ Mustang. Agreed on the reason for the Star Spec fan base. As far as the small cars go, the ST classes tend to be made up primarily of small cars, hence the number of posters driving them. I have one guy in an STI I have to run against in STU and he does very well on the Star Specs. I could beat him when my MX's were new but now they just don't have the grip. I think he is getting faster too so I will need a good tire to stay with him.

I wonder how well the Nitto would work. I once had some 555RII's on my car and I really liked them, but they were 100 treadwear and I could not use them in street tire classes. At $200 a pop plus shipping I would'nt want to take a chance on them unless I knew in advance how they would perform.
 

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I wonder how well the Nitto would work. I once had some 555RII's on my car and I really liked them, but they were 100 treadwear and I could not use them in street tire classes. At $200 a pop plus shipping I would'nt want to take a chance on them unless I knew in advance how they would perform.
I feel 100% the way you do. I'm needing a tire to drive on, autocross on, and open track on. I'm not as concerned about autocross as I used to be, though. However, we have a once a year thing with the pro-touring.com folks and they have an 140+treadwear/street tire division and i'd like to compete with them.

If I didn't have a treadwear to abide by, i'd probably be running the RII's or R888 Toyo's
 
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