Kumho Ecsta MX for Open Track Duties? - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 23 Old 01-17-2006, 08:23 PM Thread Starter
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Kumho Ecsta MX for Open Track Duties?

Just wondering if this tire will work for someone that plans to opentrack twice a year. The setup planned is:

front 265x35x18 9" rim
rear 295x35x18 10" rim


Thanks


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post #2 of 23 Old 01-17-2006, 08:26 PM
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Quote:
Originally Posted by blacksnake305
Just wondering if this tire will work for someone that plans to opentrack twice a year. The setup planned is:

front 265x35x18 9" rim
rear 295x35x18 10" rim


Thanks
A 295 is too wide for a 10" wheel and the front to rear diameter difference will disable your ABS.

Next question?

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post #3 of 23 Old 01-17-2006, 10:46 PM
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Other than that, the MX is a terrific track tire for someone who doesn't want to swap tires from street to track. That's why I'm on my 4th set
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post #4 of 23 Old 01-18-2006, 07:52 AM
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This will be my 3rd season with the MX tire. It is a really good tire for track & street. I have nearly 22k miles, 5 OT events, & 4 trips to the Drag strip on mine and they still have a decent amount of tread left. As they wear, they seem to get better and better on the track. On real hot days (like the July trip to Gingerman with SAAC) they tend to get a bit greasy by the end of the 20 minute sessions. Other than that, I like them. This year however, I am going to be switching to race rubber for my track days

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post #5 of 23 Old 01-18-2006, 12:07 PM Thread Starter
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Quote:
Originally Posted by Glenn
A 295 is too wide for a 10" wheel and the front to rear diameter difference will disable your ABS.

Next question?
hmmm. I currently run a 285 nitto (narrower i know) on a 9" with NO rim hangover, so I figured a 10" would make easy work of a 295. And according to tirerack, the 295 works on a 10-11.5" rim.

Next question? ok... why does Kumho state that the 275 tire weighs in at 19.9lbs while the 265 is portly at 27lbs...?

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Last edited by blacksnake305; 01-18-2006 at 12:14 PM.
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post #6 of 23 Old 01-18-2006, 12:13 PM Thread Starter
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And per Glenn's statement on ABS, why does this 'disable' happen? Can I proram this issue away?
I'm running 450bhp. Since I am no longer running drag radials (in an effort to be more $ effective and OT ready), I surmise i need a little larger contact patch to offset the fact that I won't have as sticky a tire on back (as I still like to have fun on gratiot on occassion) and would like to avoid breaking loose in 3 gears....

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post #7 of 23 Old 01-18-2006, 05:06 PM
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Avon Tech R on clearance sale at $139 each at Tire Rack. Oops already said too much...

particularly non-stock 99 Cobra w/brand C motor...
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post #8 of 23 Old 01-18-2006, 05:09 PM
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Quote:
Originally Posted by blacksnake305
Just wondering if this tire will work for someone that plans to opentrack twice a year. The setup planned is:

front 265x35x18 9" rim
rear 295x35x18 10" rim


Thanks
By the way, watch out for hydroplaning in the rain with wider rears vs fronts. The rear end becomes very happy. I experienced this and it's not fun. Something to keep in mind.

particularly non-stock 99 Cobra w/brand C motor...
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post #9 of 23 Old 01-18-2006, 05:21 PM
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Quote:
Originally Posted by blacksnake305
And per Glenn's statement on ABS, why does this 'disable' happen? Can I proram this issue away?
Because the ABS works on the principle of wheel speed. Once brakes are applied it uses the wheel speed data to determine which, if any tires are starting to lockup. The ABS system will momentarily release hydraulic pressure to the caliper of the wheel moving too slowly until wheel speed data matches that from the other sensors. To do that it must have accurate wheelspeed input data. With a difference in tire diameters the wheel speeds will not match front to back. If the wheel speeds are different with no brake applied the ABS computer assumes a system malfunction, turns on the ABS warning lamp and shuts the system down to prevent an accident due to faulty data iinput.

As for the 295 tire fitting a 10" wheel, go for it if you must. But, FWIW I run 10.5" wheels and a 295 is too wide for my wheel. I'm going back to a 275 on my next set. Just because you can squeeze that large a cross section tire onto a 10" wheel doesn't make it a good fit. Use a wheel size that is at least in the middle of the range for the tire being considered and you will put down a bigger footprint and have better turn-in. A narrow wheel lets the tire sidewall flex excessively resulting in a slow turn-in and less precise handling. For drag cars this isn't as big an issue and guys commonly run slicks wider than the wheel width. With a track car you want the wheel width and tire width to be matched as well as possible to improve stability.
Quote:
Originally Posted by blacksnake305
why does Kumho state that the 275 tire weighs in at 19.9lbs while the 265 is portly at 27lbs...?
They don't. The Kumho website states the 265 is 26.1# and the 295 is 30.5#, man those are some heavy tires. My V710 in 295-40-17 is about 5# less per tire. I guess the 18" sizes weigh more? I know the 18" wheels are heavier, but the tires too?

Last edited by Glenn; 01-18-2006 at 08:09 PM.
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post #10 of 23 Old 01-18-2006, 05:25 PM
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Quote:
Originally Posted by serpentnoir
Avon Tech R on clearance sale at $139 each at Tire Rack. Oops already said too much...
Ordered mine today!

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post #11 of 23 Old 01-18-2006, 05:35 PM
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Quote:
Originally Posted by Glenn
Ordered mine today!
Maybe I should have ordered two sets.

particularly non-stock 99 Cobra w/brand C motor...
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post #12 of 23 Old 01-18-2006, 07:58 PM Thread Starter
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Quote:
Originally Posted by serpentnoir
Maybe I should have ordered two sets.
glenn. thanks for the education.

Eric: I run 18's

And thanks all. FWIW, i dont think I want to make my Vert a pure OT car. I think I will need to get a heavily used 99' cobra and get real serious (when that time comes). For now, this pig vert will see street duty w/ occassional OT time (but only for the fun of it). Now I dont feel so bad about my heavy ass wheel/tire combo. LOL...

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Last edited by blacksnake305; 01-18-2006 at 08:04 PM.
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post #13 of 23 Old 01-18-2006, 08:18 PM Thread Starter
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They don't. The Kumho website states the 265 is 26.1# and the 295 is 30.5#, man those are some heavy tires. My V710 in 295-40-17 is about 5# less per tire. I guess the 18" sizes weigh more? I know the 18" wheels are heavier, but the tires too?[/QUOTE]

acutally they do, remember i'm talking 18". the 275x35x18 weighs less than the 265x35x18. I'm just wondering why...

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post #14 of 23 Old 01-18-2006, 08:29 PM
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Quote:
Originally Posted by blacksnake305
acutally they do, remember i'm talking 18". the 275x35x18 weighs less than the 265x35x18. I'm just wondering why...
I must have misread and thought you meant the 295-18. It must be a misprint, I can't see it being lighter unless it uses Aramid belts instead of steel.
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post #15 of 23 Old 01-19-2006, 08:07 AM
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I run a 315 on 10.5" 03 Cobra rims and the outermost part of the sidewall is pretty much in line with the lip of the rim, i.e. I could run a straightedge across the tire and it would contact the rim. I don't think that's too wide, is it?
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post #16 of 23 Old 01-20-2006, 04:38 PM
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Glenn, I am not saying your right or wrong on the ABS issue but... My buddy has a 1999 Cobra with 245-45-17 front 275-40-17 rear with no ABS issues whatsoever. I just called him to ask that even though there is no ABS light on if it is still functional. He says ABS works great and that he has had no problems with it. Take it for what its worth, just thought I would say something.

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post #17 of 23 Old 01-20-2006, 04:54 PM
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Quote:
Originally Posted by LT1HAHA
Glenn, I am not saying your right or wrong on the ABS issue but... My buddy has a 1999 Cobra with 245-45-17 front 275-40-17 rear with no ABS issues whatsoever. I just called him to ask that even though there is no ABS light on if it is still functional. He says ABS works great and that he has had no problems with it. Take it for what its worth, just thought I would say something.
Well, I'll take no issue with your statement because I'm sure that it's true. A 245-45-17 Kumho MX is 25.7" diameter and so is a 275-40-17 so there should be no problems. I think in a Nitto 555 works out the same as do most other tires ofthe same brand. But a Kumho MX 265-35-18 is 25.3" diameter, while a 295-35-18 is 26.1" diameter, a difference of over 3/4". Now that, my friend, could very well cause major problems.
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post #18 of 23 Old 01-20-2006, 05:01 PM
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Quote:
Originally Posted by huesmann
I run a 315 on 10.5" 03 Cobra rims and the outermost part of the sidewall is pretty much in line with the lip of the rim, i.e. I could run a straightedge across the tire and it would contact the rim. I don't think that's too wide, is it?
Maybe, maybe not, every manufacturer seems to come up with different dimensions on tires of the same numerical size. What I see when I read that a tire is 315mm size, is a 12.5" section width, which IMHO is too wide for a 10.5" wheel. I would think a 11.5" wheel would be a better match. Then again, everyone has different ideas about what is and is not a good fit, so YMMV.

Last edited by Glenn; 01-20-2006 at 05:15 PM.
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post #19 of 23 Old 01-20-2006, 07:31 PM
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Quote:
Originally Posted by Glenn
Maybe, maybe not, every manufacturer seems to come up with different dimensions on tires of the same numerical size. What I see when I read that a tire is 315mm size, is a 12.5" section width, which IMHO is too wide for a 10.5" wheel. I would think a 11.5" wheel would be a better match. Then again, everyone has different ideas about what is and is not a good fit, so YMMV.

Well, there's "ideal" and then there's "workable". Generally, wider rims are more "ideal". See Carroll Smith or Wm. Mathis books.

Kumho 710's seem to run wide. 275's look better (i.e., straighter sidewall) on my 10 1/2" rims than on 9" ones.

Even so, I'm going to try 315's this time around. If I like them, I may finally spring for some even wider CCW's. Those 315's are some expensive tires, so I will be sure and check my alternator output first.

Also, I think you can get away with more in auto-cross than for track use. Or at least due to class rim width restrictions, you see a lot of very wide tires on not so wide rims on very quick machines. E.g., 275's on 8" rims on F Stock Mustangs and also on D(?) Stock Rx8's. So, "workable" seems to trump "ideal", especially if there's no choice/budget, etc.

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post #20 of 23 Old 01-20-2006, 08:39 PM Thread Starter
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Quote:
Originally Posted by Glenn
Well, I'll take no issue with your statement because I'm sure that it's true. A 245-45-17 Kumho MX is 25.7" diameter and so is a 275-40-17 so there should be no problems. I think in a Nitto 555 works out the same as do most other tires ofthe same brand. But a Kumho MX 265-35-18 is 25.3" diameter, while a 295-35-18 is 26.1" diameter, a difference of over 3/4". Now that, my friend, could very well cause major problems.
On that note, a buddy (who ran at gingerman last year) has a bullitt w/ 245 up front and 315 in the rear. No issues w/ ABS...

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post #21 of 23 Old 01-20-2006, 08:55 PM
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Quote:
Originally Posted by blacksnake305
On that note, a buddy (who ran at gingerman last year) has a bullitt w/ 245 up front and 315 in the rear. No issues w/ ABS...
Again, no difference in overall diameter. A 315/35/17 is the same as a 245/45/17 tire. Do the math and prove it to yourself.
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post #22 of 23 Old 01-20-2006, 09:13 PM
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Quote:
Originally Posted by rfloz
Kumho 710's seem to run wide. 275's look better (i.e., straighter sidewall) on my 10 1/2" rims than on 9" ones.
So, you did break down and pick up some 10.5" wheels then, eh? I really liked the fit of the 275/40/17 V710's on my CCW's too.
Quote:
Originally Posted by rfloz
Even so, I'm going to try 315's this time around. If I like them, I may finally spring for some even wider CCW's. Those 315's are some expensive tires, so I will be sure and check my alternator output first. .
Ok, rub it in...

I might have done better with a 315/35 this past fall than I did with the 295/40's I bought. The diameter of the 295 is a bit much and I have some minor clearance issues at the rear of my front bumper cover. Teh 295 is also noticebly heavier and the acelleration off a corner wasn't as crisp. With the shorter 315's I wouldn't have the clearance problem, however I might have run into some inner fender problems instead. If you get the 315's let us know how well they fit Bob.

If you decided to upgrade your wheels again, what size wheel would you consider and what backspacing?
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post #23 of 23 Old 01-22-2006, 11:32 AM
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Quote:
Originally Posted by Glenn
So, you did break down and pick up some 10.5" wheels then, eh?

If you get the 315's let us know how well they fit Bob.

If you decided to upgrade your wheels again, what size wheel would you consider and what backspacing?
Hey Glenn-

I just got some more cheapo 10 1/2" R replicas. My 9 1/2" Borbets cracked on me and I had to use my street wheels - 9" R-58s in front and the 10 1/2" replicas in the rear.

Tires will go on next week and be tested at our 2/12/2006 event. I'll try to post my thoughts.

As to yet bigger wheels, I need to see how the 10 1/2"/315 combo fits up front (rear's not a problem). I rolled the fender lips, removed the plastic fender liners, got new hubs and longer studs, rack limiters, etc. I'm going to try 1/2" MM hubcentric spacers which will give me 6 1/2" BS. That should clear the outer fender okay, we'll see about the inside.

I'd love to go to 12"/335 like the Camaro guys, but that will hit everywhere front and rear. So, maybe 11 or 11 1/2" and 315's. In any event, I'll stick to 17" as the cost factor for 18's makes no sense to me.

If you're tired of those old and crusty CCW's, let me know.

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