So, now that we are a good way through the season, what does everyone think about the Hoosier vs Kumho so far this season?

I FINALLY got to run on the V710's this past weekend in Salina at our Midwest Divisional. Salina has THE best concrete that I've ever been on, our course was basically 3 seperate slaloms, one 5 cone, one 3 and one 8 cone with a couple of transitions and one turn-around. My first impression was, Damn, these things turn in slow compared to the Hoosier, I had to be smooth and early compared to the Hoosiers. They felt somewhat sloppy in comparison to the A3S04/A3S05's, but, grip may have been better, I know my launches seemed to be significantly better with the V710's.

One thing is for sure, the V710's will last longer it seems, but, I'm not concerned about wear on this post, only which tire is quicker. I'm trying to pick my tire for the Prosolo and National Championship since STX isn't going to happen for me this season. So far, I think I'll probably try the 710's and the A3S04's at the Pro and then decide which tire to go with at the National Championship.

My main confusion is, the Hoosier felt better to me and more predictable but I suppose thats because that was my 1st time on the 710, although I PAX'ed 1st throughout the weekend by .7 seconds and actually beat SS, BS, CS(4 top 10 CS drivers), DS, ES, FS, HS on raw time so I'm thinking they are faster than the Hoosiers, but, it was definitely a Mini type of course so I don't know if it was just the course or the tires.

What do you guys think? Hoosiers or Kumho's?? I hear many of the non-mini drivers raving about the V710's, so, thats my guess, but I'd like to hear everyone's input and experiences as well.

 

Wish I could tell you, but since I can't seem to get my hands on a set of V710's, I'll be running a new set of S05's this weekend at the tour. I'll happily swap halfway thru if you want , for informational purposes of course.

 

I recently switched from STX to DSP and the 710's. I can't compare them to hoosiers because basically all I've driven on in my 2+ yrs of autoxing is street tires, mostly azenis rt-215's. Also I have 2 deg of negative camber in the front.

The 710s are a blast -- I think they turn in quicker, and the extra grip is a joy. They start to lose some grip when they get over 150 and most folks run them at much lower pressures.

 

Maybe the pressures were my issue, or then again, maybe the Hoosiers are just exceptional and I'm not use to anything less. I wish I had some more time to tune before Peru. I was taking the temp measurements and they seemed to be OK on the pressure, but, then again, I was on the ultra-grippy concrete in Salina, which always requires a bit higher pressure. Does anyone have any good data on what pressures to run on the GS 16x6.5 wheels?

 

I have not run them on concrete. I started at F40 R42, and have moved down to 32F 28R. I've run on them 4 times now.

 

First off as some of you here may know I am NOT a big Kumho fan, the only "R" compound Kumho tire I will ever recommend is the V700 Victoracer.

That said.....

What your feeling on turn in probably won't go away with pressure. I've heard the same complaints from some VERY good AS, CS, ES, ESP and SS drivers that have tried them. Of that group the only ones still on 710's are high HP rear wheel cars in AS, SS and ESP, I don't expect the AS and SS cars to switch but after our last event the remaining ESP cars (4 drivers) will probably be back on Hoosiers at Grissom. On ome car they just plain went "greasy" half way through their runs, even after cooling them to under 80 degrees before each run. Yes the S05 will also overheat but mostly in two driver situations. With proper cooling they seem more manageable.

Personally I think a lot of "tire warmers" will be out of work at Nationals this year.

My Celica will be on freshly flipped 50+ run S05's this weekend at Grissom and I expect to be trounced by all the Mini's, maybe....

 

Well.....have you ever paxed #1 before? If not, then I think you have your answer

I am a Kumho fan and do not like how the Hoosiers that I have tried have felt or worked.
I have not been on the S05 yet and likely won't throw my money away on a set.
The MiniS drivers around here think that the 710 is the tire to have FOR SURE. They are saving the things(They call them their "good set") for big events. I will agree with them that Kumho sometimes has availability issues.

Different strokes for different folks.

Most of the top dogs in our region that were running Hoosiers have switched over from Hoosier to Kumho this year and have been getting great results and wear.

Almost no one around here is still on Hoosiers....I wonder how sales are going....

FM

 

Arrgh! I just typed up a long explaination of what we've learned, then lost it all.

So, here it is in brief, what *I* beleive:

1) Neither S05 nor V710 handle heat much differently, I'd probably give the edge to the V710 though, two Pro Solo runs and they're going away in equal conditions.
2) It's possible the S05 would be better on concrete while V710 would be better on asphalt (no new news)
3) Clearly the wear is better on the V710
4) Clearly the response is worse on the V710 (sloppy feeling)
5) Ultimate grip is basically the same

Although we were truly just learning them this past weekend, here's my thoughts on the Kumho setup:
1) Pressures on concrete were best at 38 psi front, bled to stay there.
2) Rear pressures are simply determined by setup, but we run the same psi all around with DA's in the rear.
3) It was very clear that we had extra grip when we cooled the tires below 100 degrees before the runs in the Challenge. It was also clear that once they hit 140+ degrees, they were gone.

Again, this is only what I know from talking to people and messing with pressures and a pyrometer at the Oscoda Pro Solo. I don't think I'll do any testing on asphalt until after Nationals and I'll most likely will be running Kumhos the rest of the season because I have them, although I still have some S05 left...

Feel free to email me with any questions, or proof that I'm wrong about my findings, I'd appreciate it.
garfield@northamericanmotoring.com

Hope this helps,
Brian

 

I think you know where I stand on the Hoosier/Kumho debate.

To me the best comparison came at Wendover, with Chiles going to new V710's on Sunday morning and putting the hurt on the rest of GS.

And Patty Tunnell picking up a bunch of time Sunday morning too, fortunately not enough to beat Mary.

Question for you and Brian

Do you think the sloppiness on turn in might be attributed to the "relatively" low pressures you are running in the front?

in the interests of tire life, we have been running significantly higher pressures than the 38psi Brian mentioned. Depends on the surface, but at least 10 psi (hot) more than that. Nobody has complained about the turn in response yet.

Pyrometer readings indicate the pressures are about right, admitedly slightly high. Remember though I have been compromising towards extending tire life, rather than outright grip. I was hoping to drop pressure at Nationals where grip will outweigh tire life.

Given the above posts though, I might be tempted to stay with the higher pressures.

Local events only - the V710's would win hands down, I have over 110 runs on one set now, and the cord is barely showing at one of the tread lines, not the outside edge. In San Diego - Hoosiers - we had cord showing after 18 runs (some practice, then 2 drivers x 3 runs x 2 days)

Final question - were the tires you ran heat cycled beforehand? Just curious.

Grant

 

Thanks guys for the input, its much appreciated, I'll post after Peru to give you my input whatever its worth. Hopefully before now and nats, we can put a handle on these things and catch our data up to the guys that have been running them all season. ;-)

Grant

I was running significantly higher pressures and my 710's definitely were sloppy compared to the Hoosiers.

I think driving style has a lot to do with it.

The smoother you are on the 710's, it seems the better they react and having to guess how early one needs to be is significantly reduced.

I am definitely not a smooth driver, but, when I did smooth things up a bit in Salina, I had seen a significant drop in my time because I wasn't having to "guess" on my timing on the turn-in as badly. This "guess" work is not needed with the Hoosiers IMO.

Honestly though, this was my first event on the 710's so I am keeping an open mind with my assessment. At Peru, maybe I'll try dropping to 40 or so and see what happens.

Craig

 

Craig,

the smooth driving may be the key.

Good luck in Peru. Wish I could make the trip.

Mary seems to be on the other side of the fence. She felt she battled in Atwater (Hoosiers) and then the car was perfect in Wendover (V710's). She does seem to be a smoother driver than I am.

The only time I have managed to beat her in the Mini was a local event at Pikes Peak speedway. The surface is medium grip pavement and we ran Hoosiers. I drove really well, my best local pax result, and maybe Mary was a little off those days. And with the surface being pavement it might not be a good example.

The Denver Tour site is smooth grippy concrete, and in July I predict it will be pretty hot. We might get a good comparison then.

Bob Tunnell mentioned that he is running a different setup for the V710's compared to the Hoosiers, but I have not seen him to get the details. He also mentioned the vague turn in.

Let us know how Peru goes.

Grant

 

Hmmm. How about the Atlanta Pro? Chiles was on V710s and I was on S05's...

Yes, the slopiness is due to lower pressures. Any tire turns in quicker if you make it skinnier by going to higher pressures. With the Hoosiers, we are required to run higher pressures to keep them from cording AND to increase the contact patch on the shoulder. However, I *think* we have a better shape tire in the Kumho and we can run the tire where the pyrometer leads us. The Kumho sidewall is A LOT stiffer than the Hoosier, allowing for lower pressures.
Compared to many other cars, even heavier ones, we are still high.

How high is "slightly high". I drop about 1psi for every two extra degrees in the center. When we didn't bleed the tire, the tire went away significantly faster. I take this to mean that the tire was more drastically affected by overinflation.

Completely agree. We saw the fast wear in the S05 and the V710 should easily outlast any Hoosier, although the R3S04 is a close second, if not first when the V710's are run at lower pressures

Yep, scrubbed in the same way I always do my tires. However, I didn't take as much care at reaching a temperature, just getting the initial "mold" off.
What I find so facinating is that Kumho says something about 200 degree temps being ideal. Well, I've heard that it's a gradual climb that's necessary as opposed to autocross conditions.
In our case, the tire CLEARLY had more grip below 100 than it did at 140+.

Brian

 

[QUOTE=BGarfield]Hmmm. How about the Atlanta Pro? Chiles was on V710s and I was on S05's... [QUOTE]

What is the surface in Atlanta? And don't you think the colder temp's might have played into it? Not slamming your good driving Brian, anyone who gives Mark a run for his money gets my . I used Wendover as an example because the surface is somewhat similar to Topeka - WW2 concrete that is breaking up, needing patching.


[QUOTE=BGarfield] How high is "slightly high". I drop about 1psi for every two extra degrees in the center. When we didn't bleed the tire, the tire went away significantly faster. I take this to mean that the tire was more drastically affected by overinflation.

As the Mini is so camber limited I am prepared to live with pyro readings that are not all equal across the face of the tire. I accept that the outside edge is going to be a little higher (maybe as much as 10 degree F, but usually only 5*F). "slightly high" would be no more than 10*F higher in the center. Course setup and surface type might affect my tolerances a little too. example - a course with 80% of the turns left and very tight, I'd expect higher RF readings and expect the outer edge higher by 10*F (extreme example).


[QUOTE=BGarfield]Completely agree. We saw the fast wear in the S05 and the V710 should easily outlast any Hoosier, although the R3S04 is a close second, if not first when the V710's are run at lower pressures

From all my other open wheel racing experience I am still trying to adjust to running any tire in the 40 and 50 psi range. I'd really like to test some tires a lot lower than even the 38psi you mention, but $$ vs tire wear vs V710 availability has precluded that so far. I might get the oppurtunity at a local test and tune after the Denver Tour.


I have to think Kumho's recommendation is more orientated toward road racing, where you would start with a much lower psi and let the pressure build. I agree that the tires seem to go off above 140+. Jake Nygaard and I changed front tires between drivers at the Wendover Pro to overcome this problem. Might be the only solution for Nationals for two driver cars, but that kinda defeats the purpose of a tire warmer.

Or, Kumho is taking instantaneous tire temps during testing (to get the 200* figure) If we get readings of 140*F it is usually at least two minutes after a run is complete. Finish, drive at 5mph back to grid spot, take three readings on LF, then 3 readings on RF, then do the rear tires. The tires seem to lose a good bit of heat within the first few minutes (guessing 20 to 40*). this is another thing I will have the ability to test at the test n tune.

I appreciate the feedback Brian and Craig, I will let you know what we find out at the Denver Tour and hopefully the KS event the next weekend.

Grant

Sorry for the jumbled quotes, I suck at the interweb

 

Nice try on the quotes thing

Anyhow, yes, Atlanta was a little cooler. However, we both ran in the same conditions: 70 degree temps on Saturday afternoon, and I'd figure the 70 on asphalt is equivalent to 80 on concrete in surface temp.

A stat I hadn't looked at (although it's getting very ****) is that if you look at my runs Saturday afternoon, you can see that 1st left and 1st right were fast and then I immediately lost time. If you look at Mark's, his third was faster than his first. I know for sure that my tires were gone after the first two runs, in fact, I started noticing them going away during my second.
So, based on this bench racing, I'm going to confidently say that the Kumhos will handle heat a little better, but we all know the accuracy of that.

You can notice that my lead doubled from Saturday afternoon to Sunday morning when it was 50 degrees and the tires pretty much lasted all four runs.

I'm thinking that a single driver S05 on 75 degree concrete would be the way to go for Nationals (obviously colder would be better but I'm trying to be a little realistic).
So, you'll need a set of R3S04's for 100 degree days, Kumho V710s for 80-100 degrees, and S05's for 75 and cooler... The sad part is, I have them all, plus rain tires.

Isn't this fun?

Brian

 

When I single drive on 710's (not very often) I use my tire blankets for the first couple of runs unless it is 80+F. Any hotter than that or a long course or small grid gets me spraying...
When I dual drive on cool(less than 60F days) I use the tire blankets for the first couple runs and then might just let sit for next runs then spray for each drivers last runs.
It also depends on grid size/overlap/length of course/if it is hard on one side of car etc.
When I dual drive over 70F, spraying is pretty much required before driver 1 starts his/her second run.
I would rather have a tire that needs cooling versus a tire that does not get up to a temp where it grips.

I also suspect that some people who choose to run S05's will not have codrivers this year at Topeka...710's seem to be a good compromise for an autox tire though...Kumho really did make a PERFECT autox tire IMO.
It can't be too cold or burning hot(although Bremerton last year hit 100+ in the shade and the tires still worked after LOTS AND LOTS of water).

That said, the people in my region who are switching 710's between runs is increasing slightly...I have played around a little with it but my light Miata(and sold CeliGT) has a hard time REALLY overheating the 710's.
Water usually takes car of a hot tire on my car pretty easily.

If I drove a MiniS, I would have 2 sprayers going when the car came in at a Tour. Especially on outside edge of tire that is getting the most abuse.
2 sprayers are a good idea anyways just in case of a problem.
It would suck butt to go to a big event and have a $20 sprayer poop out on you. I had that happen before....
Besides, you might need more water than you think.

I talked to Rudy/Mike/Aaron about the 200F temp thing and told them that I thought that a hot 710 at autox is not the way to go.
Road racers do get a lot more wind over the tires while running than we do.
Tires like that.

FM

 

I will definitely attest to the fact that the A3S05's go away quicker than the V710's. Speaking of Atlanta and the Saturday afternoon runs, on my 3rd and 4th runs my tires were trash for sure and my times definitely had shown that compared to runs 1 and 2, I was 2nd driver as well, so, I didn't improve my raw times at all that heat if I remember correctly with the heat.


In Salina, it was around 85 during our heat for both days, I sprayed the tires after every run. On day 2, I bought a Pyrometer for the 1st time and my readings were about even on the middle reading and outside edge reading for the fronts, I actually hit 160 on the middle and outside, I think the inside front was 130 if I remember, so, now that I think about it, my pressures were probably way too high considering the outside is obviously going to be high with no camber. If I remember, my rears were around 130 at the highest point and I sprayed them down as well after all runs. Maybe thats why the turn-in felt so crappy, maybe the tires went away on me, but, in the ultra grippy concrete of Salina, the greasiness was not so evident.

anyway, we'll get a ton more data this weekend in Peru. My only worry is the rears, I need the car to rotate, I have double adjustables on full stiff on both settings for the rear and I'm running in the middle setting on the fronts. I'm thinking of maybe trying 40-44f/50r? Well, I guess its all a crap shoot to this point, maybe I'll get there in time for a quick test and tune on Friday.

 

Thats for sure, I definitely run out of water at almost every event. You'd think my bone head would learn to go fill up the 2nd sprayer some day.

 

My good friend and fellow autocrosser has only gotten 32 runs out of his set of V710's on our local asphalt tarmac - of course, it's pretty rough. A set of Azenis lasts an entire season (and then some), but the V710's got eaten up pretty quick... Courses tend to be in the 1.2-1.5 mile range, though.

That being said, he has been dominating the class by a considerable margin - in our BMWCCA chapter, he's running against modded E36 M3's in his MCS.

 

And what were HIS pressures? I'd be curious to know. We put a heck of a lot of runs on our V710's in Toledo, 54 Pro Solo runs to be exact. There appears to be plenty of tire left, but I'm not sure.

Brian

 

I've got 28 runs on my V710's on Salina, KS concrete and Peru, IN concrete, there is still a TON of life left in them, and, they are still sticky.