Heat Cycling Racing Tires...

[leadfoot]

What is the reason to heat cycle a tire? If I do not do this, will the tire wear quicker, but have more grip?

[DAVID GAGNARD]

Leadfoot;

When buying racing tires (road race tires) I saw they advertised tires and then "heat cycled tires". Asked the same question????

They told me that heat cycling (run about 5 to 10 hard laps and take them off the car and set them up for 48 hours before using again) heats them up and by letting them cool down and sit for 48 hours you actually change the molecular structure of the tire some,sorta like putting them back in the mold and re-heating them,this I'm told by the tire people makes the tire a little "harder" thereby making them last a little longer.... Also, by making the tire a little harder you may lose some "grip",they say it is negligable,but most guys running open track that I know do heat cycle new tires....

I do also, at 150 bucks apeice,I want them to last as long as possible and right now that's only about 10 to 12 track sessions per set.....

David

[Trans-Am Jim]

From the TireRack website:

"The first time a competition tire is used is the most important. During that run, its tread compound is stretched, some of the weaker bonds between the rubber molecules will be broken (which generates some of the heat). If the tires are initially run too hard or too long, some of the stronger bonds will also be broken which will reduces the tire's grip and wear qualities. Running new tires through an easy heat cycle first, and allowing them to relax allows the rubber bonds to relink in a more uniform manner than they were originally manufactured. It makes them more consistent in strength and more resistant to losing their strength the next time they are used. An important heat cycling step is that after being brought up to temperature, the tires require a minimum of 24 to 48 hours to relax and reform the bonds between their rubber molecules."

[Cobra University]

From Bob Woodman Tires...
http://www.bobwoodmantires.com/hoostiretip.htm

Tire Break-in Procedure
Proper break-in will not affect initial performance but will increase the competitive life of the tire.

The procedure can be broken down onto phases.
1st phase: The initial run
2nd phase: The length of the time the tire is allowed to "cure"

The initial run
The first laps for the tire are critical for setting up the durability and competitive life. The first session should consist of 10-15 minutes of running. The early part of the session should be run at an easy pace, with the speed gradually increased until the end of the session. The final lap should be run at the fastest possible speed. The intent is to achieve maximum tire temp on the last lap. At this point the car should be brought in and the tires allowed to cool at a normal rate. Optimally, the tires should be removed or have the car jacked up during this cooling.
During this process, the inflation pressure should be 3-5 psi higher than you would normally use. The best progression would have the driver taking 4-7 laps to accomplish this break-in. Each lap should be approximately 7-10 seconds a lap faster than the previous lap. The goal is to have the tire temp as high as possible on the last lap without "shocking" the tire during the warm up laps. In essence, no wheelspin, late braking, or sliding. The last lap should be at, or very close, the maximum possible.


"Cure" Time
After completing the above, the length of time the tire is allowed to set is possibly more important. The barest minimum for this process to be beneficial is 24 hours. (Not "the next day"). Any less than this is a waste of time. The best situation would allow a week before using the tire again.
Proper tire management is a difficult process. To accomplish this almost always requires a second set of wheels. The payoff is greatly increased competitive tire life.

[Excaliber]

I had my Yoko's heat cycled when I ordered them. $15 per tire extra. I think it was worth it.

Ernie

[leadfoot]

Bob... A perfect explanation...Thanks... Origionally I couldn't understand the difference between a day at the trace and "heat cycling day" as they both did the same think. But with the progressive heating and then the colling period explains it all.... Thanks again.