Kumho Heat Cycle Question

[Th3_Gr33k]

Ok I just ordered some Kumho Ecsta XS tires for my little AE86 corolla, and I was wondering about the heat cycle process for these tires. Has anyone used these tires before? I know I am supposed to bring them up to around 200 or 205 degrees and let them cool for about 24 to 48 hours.

My question is, how long do I need to keep them around that temperature? I will be using an infrared thermometer to check tire's surface temp. Also, I know it is getting pretty cold outside and the surface temp might hinder me from getting to the ideal operating temp for the curing process. Any ideas? Thanks.

 

[P-Funk!]

^huh?

I have never heard of having to do that after you buy tires...

Why would you?

 

[Th3_Gr33k]

When you start racing you will understand. For the longest time I would race with plain-jane DOT spec tires, because they were cheaper. But now that I need to step up game and further utilize my suspension, I need to upgrade my tires.

From my understanding, and I will try and simplify because I am supposed to be studying for an Organic Chemistry Final for tomorrow(nailbyt), the reason you heat-cycle a competition radial is because the molecular structure of the rubber hasn't "settled" yet and is very soft. You are supposed to heat up the radial to about 85 percent of its operation range (which contradicts my first post; optimal operating range, I found out, is 203). Once you have brought up the temperature the molecules are supposed to rearrange themselves. After you have finished the "break-in" procedure you are supposed to take the wheels off of the vehicle and let the tires sit for about 2 or 3 days so the molecules take their final stable structure.

Now, I cannot verify this from personal experimentation, I am not a polymer chemist. Only from what manufacturers and other people have said. Seeing as this set is my very-first set of competition radials, I do not want to ruin them. Maybe I will ask my Organic teacher tomorrow after the exam, he would definitely know. He used to work for Goodyear. He might be little bonkers, but he is knowledgeable.

 

[yangsui]

The Kumho XS' are street tires. Sure, they are cheater street tires that are almost r-comps but I don't think they are hardcore enough to require the initial heat cycling that you describe. Maybe you should call Kumho USA to confirm. If anybody knows how to prepare Kumho tires for racing, it'd be them. You might have to fish around to get someone that knows what they're talking about though.
http://www.kumhousa.com/About_Contact.aspx

If you insist on heat cycling, maybe you can send the tires to Tirerack and have them heat cycle the tires for you Or just call Tirerack and ask how long they keep the tires on their rollers during the heat cycling process. That should give you an idea of how long to keep the heat in the tires.

 

[Ty07allstar]

I would have just let tire rack do it. With all of their race tires they offer Heat Cycling for $15 a tire.

 

[Th3_Gr33k]

Well they offered heat-cycling for the tire when I purchased it, so I am assuiming that there has to be some type of molecular refomation of the tire, no? On Kumho's website they advertize it as an "autocross" tire.
http://www.kumhousa.com/Tire.aspx?id=675dce77-813e-4027-b467-2bea0466bd5c&cat=18
But I agree with you about calling them, gonna make a call later today after my final(boom06)

 

[yangsui]

Well they offered heat-cycling for the tire when I purchased it, so I am assuiming that there has to be some type of molecular refomation of the tire, no?

Real r-comp tires like the Kumho V710s should probably be heat cycled but I don't think the XS' need it.

My guess is that Tirerack just wants to squeeze a few more dollars out of the customer. The Kumho XS are sort of borderline r-comps so they can get away with it. Ask Tirerack straight up if heat cycling is really necessary for THAT tire. You already bought the tires so they'll probably be honest with you. I still don't think it's necessary but would appreciate some expert opinion as I can see Kumho XS' in my autocross future.

If you do talk with Tirerack, let us know what they say.

 

[Th3_Gr33k]

Well I called Kumho right now but the lady transferred me to the tech guy but he wasn't there so I left a message. Hopefully they get back to me. If not I am going to be a pest and keep calling.

I was talking to my Organic Chem professor today about the tires, and boy did his eye light up. He was in charge of calculating the chemical makeup for each kind of tire, and was in-charge designing a precess to to get the metal band in the tires adhere to the rubber, via dipole moments. WOW! So I asked him about the r-compounds and he said that they would put it in an oven for about 3 hours to rearrange the structure. So that basically didn't even answer my question. (sad1) But he did say that I should keep them at an 80-85% max operating temperature for about 45min to an hour, give or take a little, to really make sure they are properly oriented, molecularly speaking. But then again, I still question him. 45min seems a little to long, anyone ever heard of such a thing?!(eyeballs)

Little off topic, but I was asking him what was the deal with Firestone was, with their tires exploding and all, and he told me that the reason that they did was, not because of a bad chemist, but because they had a "limited budget" and wanted him to do the best he could with it. Unfortunately the gentleman that was in charge of the belt and rubber adhesion process passed away a couple of years ago. But then again Firestone was already known for bad tire engineering. In the early NASCAR days Firestone's engineering had failed them and costed a few men their lives because of exploding tires, and they withdrew their involvement with NASCAR.

Question: How did NASCAR get its name?
Answer: *in hick-like voice* "Hey boy, that's a nas car you got there!" (lol2)