Cold or hot tires?

Michael Czeiszperger · **Joined:** Thu Apr 09, 2009 9:35 am **Posts:** 861

I was reading that some tires work better the hotter they get and others grip better when they're cold. Now that its getting really hot outside, how do I tell what type of tire we've got? They're Kuhmos legal for the street tire class, and Maria said they were "cheater" tires, but that doesn't tell me if we should be trying to cool them down between runs or not...

Aaron Buckley · **Posted:** Wed Jun 03, 2009 2:51 pm

Michael Czeiszperger wrote:

I was reading that some tires work better the hotter they get and others grip better when they're cold. Now that its getting really hot outside, how do I tell what type of tire we've got? They're Kuhmos legal for the street tire class, and Maria said they were "cheater" tires, but that doesn't tell me if we should be trying to cool them down between runs or not...

In general, the Kumho streets like more heat, while the Kumho R compounds need to be cooled between runs to be fast. - AB

Michael Czeiszperger · **Joined:** Thu Apr 09, 2009 9:35 am **Posts:** 861

Aaron Buckley wrote:

In general, the Kumho streets like more heat, while the Kumho R compounds need to be cooled between runs to be fast. - AB

I know nothing about tires. How do I find out if the tire is an R compound? I thought that material was for racing slicks?

Aaron Buckley · **Posted:** Wed Jun 03, 2009 2:58 pm

Michael Czeiszperger wrote:

I know nothing about tires. How do I find out if the tire is an R compound? I thought that material was for racing slicks?

I doubt it is. What is the tire model? - AB

Michael Czeiszperger · **Joined:** Thu Apr 09, 2009 9:35 am **Posts:** 861

Aaron Buckley wrote:

I doubt it is. What is the tire model? - AB

I'll check when I get home tonight. Thanks for the help!

Richard Casto · **Posted:** Wed Jun 03, 2009 3:04 pm

Michael,

Aaron will stear you in the right direction, but regarding "R compound" tires, the simple answer is imagine making a DOT regulation tire, but by using racing rubber compounds and other racing tire ideas. These are street legal, but one step below racing tires. Or another way you can say this is that they are racing tires that have been built to also meet DOT regulations.

It would be highly unlikely that your every day street tire is an "R compound" tire.

As Aaron says list the model and someone can tell you about the tire.

Richard

Michael Czeiszperger · **Joined:** Thu Apr 09, 2009 9:35 am **Posts:** 861

Richard Casto wrote:

Michael,
It would be highly unlikely that your every day street tire is an "R compound" tire.

As Aaron says list the model and someone can tell you about the tire.

Yup, makes sense. I'm specifically asking about the tires my wife bought to autocross, since those are the tires she's using in street tire class. I'm trying to figure out if I need to cool off her tires between runs or leave 'em be. Anyway, I'll look up the numbers tonight. Earlier I spent hours google'ing the tire model numbers, and found dozens of similar entries, and no information about wether the tire should be cooled down between runs or not.

RobLupella · **Posted:** Wed Jun 03, 2009 3:26 pm

Since she is in Street Tire Class, they are not "R" comps (Victoracers, V710s), and are probably MX's or one of their other street tire brands. I know my Azenis get greasy when they get hot. As you get more experience, you will feel the tires gripping less (getting greasier). there is some complex science stuff that probably impacts the 30 seconds the tire is at optimal temperature for the heat, surface etc. :roll:

Many people bring water sprayers to keep tire temps manageable. Someone with the same type tire on the same type car can probably give you some advice on how hot is too hot, or eventually your buttometer will feel the difference.

Good Luck
Rob

Gwen Habenicht · **Posted:** Wed Jun 03, 2009 3:48 pm

OK, I’m stepping in where guys with lots of knowledge have gone before-and I’m not one of those guys. But, I just briefly looked at the tires on the cars of the gals I rode with at G’ville. (It gives me a frame of reference on how loud to yell gas, gas, gas! :shock:

) IIRC Maria’s tires are treaded, not V710s, so, pretty sure not R compounds. What’s the tread wear rating? If it’s 300-400 they’re pretty hard, so I’d think you’d want to get some heat in them to soften them somewhat. I’d suggest a good starting place for spraying might be: 1. Do they seem greasy after the 2nd run? If so, give them a spray. 2. Put your hand on them, and if they’re too hot to touch, give them a spray. Trial and error is sometimes the best method. Personally, I’m not sure how much spraying is required on a street tire, but we’ve not been on streets for a pretty long time now.

BriceJohnson · **Joined:** Thu Apr 13, 2006 7:33 am **Posts:** 2230

Your tires are Ecsta MX's. From what I know, these tires like heat. Ask Carlton Whitehead, he ran through two sets of these on his Altima and was pretty damn fast on them. I don't recall ever seeing him spray them down.

That said, I'll piggyback on this thread and ask, what about Dunlop Direzza Z1*'s? I have been spraying them just so that I have a consistent starting point for each run and to try and keep wear down a bit (these are my street tires too). At the intermediate school last year I did some "rather uncontrolled" experimentation (anyone who was there will remember me just going over and over on the short course during the lunchbreak) and they seemed to grip better cold than hot, but I'm hardly good enough to definitively say one way or the other and its not like I had data acquisition or anything.

Michael Czeiszperger · **Joined:** Thu Apr 09, 2009 9:35 am **Posts:** 861

BriceJohnson wrote:

Your tires are Ecsta MX's. From what I know, these tires like heat.

That's great, but how can you tell? Is there a spec somewhere? Or do I just need to somehow tell by looking at them?

Also, the pressure is increasing dramatically, going up 5 pounds/sq in in two runs. Should I be bleeding them off to keep the pressure constant?

Carlton Whitehead · **Posted:** Wed Jun 03, 2009 7:51 pm

I didn't water my MXs between runs more out of laziness than some kind of insight about their performance in the presence of heat.

With that out of the way, I do think the MXs like heat. My times improved pretty consistently each run, and I never felt like they were losing grip as the day progressed.

I'm actually going to be running Dunlop Direzza Z1s. I haven't autocrossed on them yet, so it'll be interesting to see if my strategy of laziness continues to work. Or maybe Brice would be so kind to loan me his sprayer? :lol:

Gwen Habenicht · **Posted:** Wed Jun 03, 2009 7:52 pm

Michael Czeiszperger wrote:

Also, the pressure is increasing dramatically, going up 5 pounds/sq in in two runs. Should I be bleeding them off to keep the pressure constant?

You betcha!

First, search for the pressure that gives you the best run. Check pressure before and after each run. When you hit on the best feel, that’s the pressure you’ll want to maintain.

Maria Winslow · **Posted:** Wed Jun 03, 2009 9:29 pm

I love how I check the forum and find that people are discussing my tires in detail

For the record, they're Kumho Ecsta MXs. I have so far figured out that 40 in the front and 33 in the back is working well, as long as I remember to let out the air after each run. To my pit crew: the car needs to be washed!

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