Kumho 710 temp question, anyone use a tire pyrometer on these? Options

[kdfoust]

I just mounted (not like that you perverts) my first set of V710 for AX. I typically tune using tire temps as a factor but I didn't get to call Kumho in Akron early enough today to get their optimum operating temp data.

Anyone got any tire pyrometer/pressure/alignment data that they want to share? Or better yet a tech sheet from Kumho?

Regards,
Kevin

[Trekkor]

Start them between 26-28 cold.

Reset to 28 before every run.

A/X temps: I can't get them hot. Not like today in 25-30 minute on track sessions in 100° plus weather. Tires were 190°-180° across the surface.

I think I remember reading somewhere that these tire work up to 220°. (IMG:style_emoticons/default/confused24.gif)


Alignment is -1.6 front and - 1.8 in rear.

KT

[kdfoust]

They still felt okay at 180?

Hey thanks for the tip. It looks like I'm setting a little short of that alignment right now at -1.2 all around. If I've got time tomorrow I'll give it a tweak.

I'll let you know what I see for temps on Sunday.


Regards,
Kevin

[nebreitling]

depends on the surface and ambient to me. messy asphalt (e.g. Santa Rosa airport) seemed to want up to around 32 and even 34. Hot concrete and I'll run 28-29 like Trekkor. Cold concrete and i'll raise them to 30-32. none of this seems to make much over-arching sense to me, but that's what i've found through my own humble experimentation.

i don't have a tire pyrometer, so i can't comment on temperatures... i've got more (neg.) camber than Trek.

[kdfoust]

Hey guys. Thanks for the tips!

I ran the V710s today. Did 14 AX passes on a primarily left hand course. It was my first time out with the .R tires so I was learning something every single pass. I do like these tires! I was able to put some heat on my nearest competitor, an early 70s 911 with a 3.2.

Today was on messy old asphalt so I decided to start with 32 psi cold. It turns out that I just left the pressure along through the day. I did monitor the pressures and temps after every session (5 runs). Coming from high end street tire I am really impressed with the lack of overheating in these tires. They felt substantially the same each pass and I never overheated them although I'm positive I wasn't getting all I could have from them either.


Here's the car setup. As you can see it's a pretty mild setup. I'm reworking it over the coming week.


Here's the raw tire data from my last run.


Here's the graph that I normally use for evaluating the car setup. You can see that the right rear had a little more heat in it. That's because I accidentally lit it up in a corner right before the finish. The car was getting a little loose or my driving was getting a little loose. I definately could have dropped the pressures in the rears as indicated by the higher temp at the center of the tire.

[nebreitling]

glad you had a good time! next time, definitely experiment with your pressures.

sitting at -1 or -1.2 camber? try a little more. if you don't mind slotting your strut towers, you can get like -2.5 or more.

they are good tires.

[grantsfo]

I agree experiment with more negative camber and lower pressures. Do you have to use 5.5" wheels for your class? I would go with wider rim as well. I wonder if those temps are consistent across the tire section with 5.5" rims?

[Trekkor]

With that many runs available you could have dropped the pressures to 28 for a least a run or two, "just to see".

Did you spot or chalk the sidewalls to moniter sidewall rollover?

I like the data and record keeping.
I wish I had been doing that all along.


KT

[kdfoust]

With that many runs available you could have dropped the pressures to 28 for a least a run or two, "just to see".

Did you spot or chalk the sidewalls to moniter sidewall rollover?

I like the data and record keeping.
I wish I had been doing that all along.


KT

No, but I could clearly see the sidewall rollover since this was the first outing on these tires. The side wall marks (or lack of) follows the pressure and temps in that it shows I could run lower pressures. Next time out I'll run temp/pressure experiments and let you all know what I find.

I'm a huge fan of data logging. I took my "other" Porsche (and my driving) from being a rolling chicance to a track record setter with the same methods over two seasons.

Later,
Kevin

[kdfoust]

I agree experiment with more negative camber and lower pressures. Do you have to use 5.5" wheels for your class? I would go with wider rim as well. I wonder if those temps are consistent across the tire section with 5.5" rims?

The is classed as POC V3 and PCA Zone 8 AI and it's not maxed out in points. I can pretty much run any wheel I want (eventually). For now it's going to be 5.5" Mahles since that's what I've got. I'm planning to put on a 5-lug conversion maybe in the spring but I'm not in a big hurry to do it.

Later,
Kevin

[kdfoust]

I talked to "Rudy the motorsports guy" at Kumho in Akron. He is recommending V710 tire temp at 140F. Past that a little cooling water is called for (sprayer on the grid). In terms of pressure a prepared or street prepared car (in SCCA parlance) would be looking for high 20s to low 30s. I was also surprised that he recommended "less camber" than most people run to allow the tire to work on the shoulder of the tire. I'm still not sure about the less camber but allowing that it's not unusual to see a car set to -3 deg... I'm gonna follow up on that camber remark tomorrow to see what we're talking about here. "Rudy the motorsports guy" also claims that the tires are designed to work well onto the shoulder. I believe this based on how far around the side of the tire the tread markers are.

So back to my data, after five passes with some wheelspin in back I'd well exceeded 140F. The front temps don't look too awful bad, still a little on the warm side, but I don't think that I want to lower the pressure (which will increase heat) any unless I'm prepared to spray between passes. The rears are clearly overcooked but that's always an possibility with the 3.2 so I'll just be a little more careful with the loud pedal next time.

I think that I'm going to monitor the temps after each pass this Saturday to see how the tire is responding. I should have at least two practice sessions plus to the timed runs to mess around with the tires. I'm picturing that as I lower the pressures to get wider contact the heat will increase dramatically which then makes the tires want a little spray between laps. For now my suspension setup will be the same since Ground Control forgot to ship my stuff...

Well, that my story and I'm sticking to it...

Later,
Kevin