mcipseric

Race tires are meant to run hard for 1.5 hours (3-4 run sessions during club sprint races...) and thrown out.

I don't see that many HC tires at pro races......

Don't know the facts on DOT tires.

mark kibort

well, its not really about just scrubbing them in. 4-5 laps, and THEN 2 laps at near full speed (90%) to get them to race temp., THEN the 24 hour rest. ill explain why below.

I agree to a point. as i have said many times, its an important aspect of racing/tracking, being able to drive on varied surfaces and tires. however, when tires become heat cycled out, or old, they can become very squirelly, near what it feels lke to run on a wet track in extreme cases. this might be good for learning, but bad and a little dangerous if you are not expecting the lack of grip on a dry hot day. there is cerain degrees of heat cycle issues. ive had R and A7s that are litterally junk even though i could see a portion of the wear bars.

No, this is not true. the chemical compound (the rubber) when heated and then cooled for a 24 hour period INITIALLY, allows the molecules to algine and provide a more stable structure. this is ONLY upon first heat cycle. it allows the tire to have more grip and last longer. there is NO downside. (or less grip)

What spencer said is not entirely correct. you dont want to overdo the initial heat cycle. you want to bring them to a normal race temp and then let the rubber sit for 24hours. this aligns he molecules of the rubber surface structure , so that its wear pattern on the next use is more consistant. it doesnt effect grip, only wear. they last longer if you heat cycle them...... you never hear of the tireRack advising NOT heat cycling them for bettter grip, right? its not a HUGE deal. ive done it both ways, and havent seen any difference, nor has many of my competitors

yep, thats the idea. i dont know the effects of overdoing the 1st heat cycle, but what you says sounds logical. certainly what you say is true on the reasons for doing a real heat cycle and rest. the cross linking /or alignment is key for longer life but dont make them softer after the first heat cycle. it just makes the tire wear better/longer.

mark kibort

Actually, due to their schedules, usually you qualify on the tires you are going to race, and the qualifying session is a good heat cycle, race or DOT tire. then, 24 hours or more later, you race on them, you race on them. thats a decent heat cycle.
I dont really know if there is a huge difference between HC'ing a DOT vs a race tire.. thats a good question.

mcipseric

good to know. Club racing on a limited budget, and racing the same day as qualifying, does not afford this type of schedule.

mark kibort

No one knows this better than me on my shoe string budget. With SCCA usually, we have practice and qual on one day and the race the next. this works out perfectly for HC'ing the tires properly..... however, you cant go nuts on qualifying, though, which is a draw back.. i slowly get the tire to temp over 4 laps and then hit them hard , but controlled for 2 , maybe 3 laps more for a fast qual lap and come in.
However, if i had a race and qual the same day, and my practice tires were decent, and practice was the day early, i might scrub in the new tires for 5 laps, take 3 more progressivly faster, and then come in.

I dont think its worth really stressing about, so if you needed the new tires for qual.... (you needed the best qual possible) And the race was the same day, i would just run the tires in qual and the race and most have said, its not that big of a deal. i dont think there is any scientific study of how much longer or better the tires wear by doing a HC and 24hour rest and not doing it. if i was to guess, maybe you get 1-2 more better races out of them, out of 8 or maybe they last 12 vs 10 heat cycles before they get hard. something like that..

JarheadGT3

**Disclaimer: I am neither a scientist nor an expert on tires. I can only cite my personal experience.**

I've exclusively run R7's on my 997 GT3 race car for two years now, and have tried:
- R7 mechanically heat cycled by vendor (Tire Rack, Phil's, etc.)
- R7 heat cycled per Hoosier recommendations (bring up to temp, 24hr rest)
- R7 no initial heat cycle

For my driving style, typical weekend schedule, and "move to DE pile" patterns, I find that the mechanically heat cycled R7 suits me best. I'm able to throw them on the car, scrub in during warm-up, qualify a few hours later (sometimes less), then run in 30-45 minute races the same day, and for the remainder of the weekend without any ill effects. That said, somewhere between 5-8 heat cycles I shift my tires to the DE/test pile and have only run up to maybe 10-12 heat cycles on an R7 ever. As such, I have no idea what they feel like beyond 10-12 HC. I will also say I don't like the "crispness" of a new R7 (especially on a bumpy track) and actually prefer the feel of the 3rd heat and 4th heat cycles for races - not too crisp, and just the right amount of slip...kinda like my Hoosier Goldilocks.

With the by-the-book heat cycle method, I've noticed no difference whatsoever in the first 5-10 heat cycles compared to using a vendor-provided mechanical heat cycle. (As others have mentioned, it may very well impact longevity and I simply haven't run mine long enough to enjoy the benefit.) With this fact in mind, I frankly prefer not to deal with the hassle of multiple tire swaps a weekend to get the proper heat cycle sessions done + 24 hour wait period. Just not worth it FOR ME. So, I avoid this at all costs and only do it if I can't get tires mechanically heat cycled due to availability or time crunch.

I have also run stickers right out of the box. When given at least a couple hours to rest between the first heat cycle and the 2nd, they seem to be okay, albeit a slightly different feel than my mechanically heat cycled tires. Can't really put my finger on it, other than to say they felt slightly less confidence inspiring in the race...maybe by 5-10%. When taken straight out of the box and tossed into a 45 minute race, I hated them. They seemed to last about 15-20 minutes into the race, then ventured into "greasy" territory for the remainder of the race. Never tried that again. As I mentioned in my opening line, though, this is in the context of my driving style. I'm a bit of a brute, and can be aggressive at times with the car in traffic and on defense, resulting in the need for some slip angle without overheating the tire. I think that probably had a lot to do with the stickers going greasy on me - if I were more a finesse driver, I may very well have had a different experience.

So, bottom line, what suits my needs the most in an R7 is the "set it and forget it" mechanical heat cycle service. The grip is there when I need it, and it's less work I've got to do with session timing and tire swaps on a self-supported weeekend. YMMV.

Beantown Kman

^^^ Agreed. I've been running R7's since they first came out. I've tried all the different varieties of heat cycling. And I've run them without heat cycling. There are so many variables that will affect how well a tire performs and how long it will last that it makes it difficult to compare processes apples to apples.

Hoosier ran a tire webinar last year through Motorsportreg.com. I watched it and listened to their track guys talk about heat cycling. They strongly recommended the process. They explained exactly what happens when you heat cycle your tires. They were less clear about what exactly constitutes a heat cycle. And that's the problem I've had.

It's not easy to get a R7 up to race temps unless you're pushing the car pretty hard. And that seems to be at cross purposes with the principle of not pushing them too hard while trying to "scrub them in".

Bottom line: $60 to mechanically HC a set of 4 tires from the vendor seems like an inexpensive, consistent and effective way of getting the job done.

Frank 993 C4S

It’s consistent what Spencer told you about the initial heat cycle.

mark kibort

thats why i like to run the new tires in qualifying. you get great grip... you get a fast lap.... you bring them gently up to race temp, and then hit them for 2 laps all out, but no sliding around. (100% , not 110% like some might run them in a race) then, its natural to let them sit overnight before the race. works out well and you save $60 .

as far as racing out of the box on a R7 or A7, i dont think ive heard of any performance difference vs a heat cycled tire over a 30 min race, where they go away at 20min. that can be any tire , in my opinion and experience depending on the driver and race conditions.

987part

I only have 1 year of experience on racing slicks.
But my last PCA race at road america , i was on 3 HC tires , qualify and 2x sprint races(putting 2x track records)

Tires were garbage during enduro.
On the 1st lap, i couldnt even keep the car on track. Not very pleasant for 90mins.

Even sprint 2, they were 70% good

I also think it depends a lot on how hard you push the car.

nxfedlt1

so to bring this back up, I spoke with an engineer for the R7s at PRI at was told this :

- tire rack or other similar heat cycling processes do not work, and to save your money;
- the initial heat cycle will extend the life of the tire ~15-20%.

He was very technical too, and that was quickly over my head! I did take away that I need to run a higher PSI as I've been trying to run these at 36 hot, and he said for the 991 GT3 to run at 38-39, and shoot for 210 deg.....all that to say, I have no idea what my tire temps are now, so more things to buy, woohoo!

mark kibort

hahaha! seasoning the brake rotors? with what , salt? you probably bed them on your first few laps and dont know it... we all use autox tires now on road courses, most under inflate the tires a bit, i haven't tried your "rains" technique, but then again, it doesn't rain in California.

i dont think any "sticky parts" leave the tires.. its a molecular alignment that happens when the tire cools for 24hours. probably analogus to a forging process. otherwise, the alignment doesnt happens and the tire wears faster. i havent see this , as they seem to just heat cycle out before they wear out.

mark kibort

did he mention anything about A7s?

by the way, does everyone agree that on the super speedway, that the tires need to be over inflated? ive heard, 40psi cold . im going to a superspeedway for my first time and want some feedback .
generally i run kind of low pressures at the tracks i visit with the A7s and A6s. 30 to 32 hot. when in the 35 range, it seems that the centers are unusually hotter. than the outers., which i thought would be the best indicator.