I've heard varying reports about the merits of Tire Racks' heat cycling process. Does anyone know if this is indeed worth the extra cost for race tires (over doing it yourself- not always possible for me)? Is there any documented testing proving its merits? What temperature are the tires taken to? For how long?
I've always purchased tires from them and been happy with their service but my local supplier offers the same tire for less (not even including the shipping costs) and I'd like to support their business. My major reason for using tire rack was the heat cycling- and now I'm not so sure... any information is greatly appreciated.

 

George, put me in the group of doubters on this issue. Some people swear by it.. I don't think it's a moneymaker for Tire Rack for that matter, but my personal track wear and handling experience, having burned thru a bunch of BFG R1's and Hoosiers with and without the yellow heat cycle stamp, hasn't left me convinced one way or the other.

 

FWIW, my tire guy (Grand Am racer, truly an expert on race tires, owns Radial Tire Co.) claims that for club events, heat cycling is a waste of time and money. He swears it gives you one-to-two more sessions over non-heat-cycled tires. Maybe in a 3-hour pro race or an eduro it's different, but I'm taking Paul M.'s word for it an foregoing the heat cycling.

(Your tire wear may vary, etc. ...)

Lee in D.C.

 

Kumho Tires recommends that Heat Cycling be done...thay also recommend you shave the tires from 6/32 down to 4/32. If I can find someone to shave the tires in SoCal, I am going to try it this time. I have some brand new VictoRacers coming.

Kumho also recommends 2 to 3 degrees of negative camber in their article "Care and Feeding of the VictoRacer Tire". I don't want to drive on the street with this much - camber, in addition, the most I have been able to get out of the fronts is - 1 1/2 degrees.

In addition they recommend a probe pyrometer (done right when the car comes off the track) to be certain the temps don't go over 220 degrees F, they say that a max of about 200 is best, and it is important to measure the temp delta across the tire. A good wearing tire (proper camber) should not vary more than 20 degrees across the tire.

I don't think that Tire Rack is making a fortune heat cycling tires.

 

I spoke with a Kumho tech rep and he says HC will add a little life but he contends the more important aspect is that it keeps the tire more consistent over it's life. I ran one set w/o HC and did notice the tires lost grip well before they were worn out. Since I've started HC I've had rears down to the cord and they still had grip which in my mind validates his consistency theory.

Here's how he HC his tires. Go for about a 30 minute leasurely ride just to get the tire up to temp and then find some twisties to scrub the outside edges and put a little heat in them. Take the tires off the car and let them sit for a couple of days. He cautioned against too much heat both in the HC and the first time out. He said if a new tire is taken up to competition/DE temps too soon the molecular structure of the rubber is changed and causes the tire to be inconsistent as it wears.

I've had Tire Rack do the HC and have done some myself using his process. Both with good results.

 

When you heat a soft compound and allow it to cool for 24 hours or more, the bonds in the molecules break down with the heat and reform with the slow cooling. The provides for a stronger tire, which results in greater life. This is usually only a couple of additional heat cycles for the life of the tire. Not a big deal for a DE tire, plus it is very hard to get enough heat in the tire to really cycle them, unless you are on the track.

Another important aspect with many race tires is that they go through a 'greasy' stage in the first cycle. This is not something you want during a race, but again, is no big deal for DE's.

For DE tires, I heat them as best I can on the street - drive highway for ~20 minutes then find a deserted wide road and do lots of swerving back and forth, like warming a tire on the pace lap of a race. Drive the car home and let it cool for 24 hours or more. If the garage floor is especially cold, you should raise the car, otherwise it doesn't matter. I am not sure how much good that really does, but it can't hurt and it is easy to do.

 

I'll go along with Buck and Mark D.; heat cycle them. Local shop that race-preps cars recommends it and so does tire manuf.

 

I have always had Tire Rack heat cycle and shave my tires for DE's. Was it worth it? I think so.
I have already driven my Kumho's at Sebring for 6 days and I still have a ton of meat on them.
And they are extremely grippy.

Also, two other things I would like to note about the Kumho's.
I was advised by my seller (luke at tirerack) that even though Tire rack heat cycles the tires, your first session you do not want to go 10/10's for extended periods of time. Reason is.. Even when heat cycled, Kumho's have a tendency to run extremely hot the first time there used on the track. So, maybe run a bit conservative and give yourself some extra time for extended cool downs when you first get the tires. But after your first session, your good to go.
Also, I have never driven on Hoosiers so I can't give you a good comparison, but I found that the Kumho's are excellent tires. Yet they take a while to get real sticky and hot. Like three laps at Sebring. The guys driving Hoosiers told me that Hoosiers got hot quick but by the end of the session, they started to get loose.
On the Kumho's they will start a bit loose till hot then grip will continue to improve until the end of your 1/2 hour session.
again, I am no expert. But conversations I have had with people driving on Hoosiers helped me come to this conclusion.
So don't be surprised if your 2 laps into your session and you still don't feel the tires are gripping that strong. By your third lap, you'll be catching up to all those guys you had to point by.
Just my Opinion.

 

If heat cycling was so important (I am not arguing it is not important) for a competition tire, why wouldn’t the manufacturer do that on the production line? It would cost them very little and they would be offering a higher performance tire?

Regards,
George
In sunny AZ

 

Good question George.

To tell you the truth, I have no good answer for that one.
But I am by no means a tire expert. Rather, I no little to nothing about tires.
I continue to heat cycle my tires through Tire Rack because to date, I have had no bad experiences doing so and my tires seem to last long and hold up very well. They might perform and hold up just as well without it, but it's not that expensive to do.
I might save a couple bucks by not doing it but when I find something that works, I try to continue doing it. Tires are expensive and if I can get another 2 sessions or half day on them, in the long run it all works out.
I don't think it will make a huge difference either way.
--oh yeah, I think the Kumho V700's are not a competition tire, they need to be shaved for my purposes/track.