Soloontario

All of the above mentioned tires work far better than street tires of even a few years ago and I know that in AutoX, you can get a lot of runs from them. OTOH, (and I don't have enough experience or hard data with either the Rivals or RS3s that I have run) I am suspicious that after a number of track sessions that the rubber hardens up on these tires, not like a Kumho V710 or Hoosier, but still the tires don't perform as well as new. My experience with both V710s and R6s is that they heat cycle out at exactly the rate the manufacturer suggests, ie. 16-18 heat cycles for the V710 and fewer for the Hoosier.

Anyone have hard data rather than my very anecdotal assessment?

BTW I am looking at track use with prolonged i.e at least 10 to 30 min heat cycles, not short 1-2 min autoX runs.

JiminVirginia

I don't think they are soft enough to heat cycle (which means breaking and reforming bonds continuously with each use until the structure of the tire can't evolve any more). They can wear out, but that is very different.

I'd be interested in any evidence to the contrary.

Xian

Yeah, they can cycle out but that's less likely to happen if it's a DE tire because you'll have longer runs and more wear on them per cycle. If it's a DD'er and autoX tire, the day to day use of the tires will absolutely make them cycle out before they wear out. As "street tires" have gotten closer and closer to the R-comps of ~15 years ago, it's become more common/apparent. Most folks will still be able to get a year/season out of a set of tires but expect them to drop off at the tail end of that timeframe.

^^^ talking about the current and prior crop of "Extreme Performance" stuff; harder tires are less susceptible to cycling out.

tytek

That is interesting. I had a suspicion that some of the extreme street tires tend to lose grip over time. When I ran street tires on the track, I could feel them get less grippy towards the end of their useful life span. Initially, I would have very little understeer, until the tires got really hot at the end of the session on track. After 6-7 track days, these street tires would get greasy and I would have massive understeer right after just one lap. So you may be on to something...

Chets LS3

If you read in my other thread I have re-11's and im pretty sure this has happened to me:

still 3/4 32's of tread left, the tires are driven on the street, 1+ season of auto-x, and 4 hpde runs and it feels like im driving on an ice rink.

RX-Ben

Anecdotal. On DZ101s I lost 2+ seconds and they felt like crap after one hard day.

FAUEE

If your street tires are heat cycling out, that's a HUGE drawback to running that category for anyone but the people who are truly chasing the competitive edge. If you're just doing HPDE, that's a MAJOR shortcoming in the tires.

I'm going to be PISSED if my Falken RT-615k heat cycle out. Only being able to use them for maybe a year's worth of events is unacceptable in today's day and age.

Soloontario

What is particularly irritating is that older R comps like the Toyo RA-1 (and I would guess Nitto NT01) were very resistant to heat cycling damage to their performance. They were never particularly fast but almost performed better the closer they got to the cords. So obviously the magic involved in the compounding already exists.

(Don't get me started about the Toyo 888 which to me heat cycled out like a Hoosier while performing like an RA-1)

What we may be looking at now is street tires, that like other high performance tires, run out of grip long before they run out of rubber. I was hoping that this wouldn't be the case and would love to be proved wrong.

strano@stranoparts.com

Yes, they do.

Xian

The RA-1 phenomenon you describe isn't a magic compound; it's grip improvements as it wears are due to lower tread squirm outpacing the tires heat cycling out. The result is that the tire was "amazingly consistent from full tread to the wear bars". If you shave it down to 2-3/32nds it's measurably faster and better in the dry but doesn't last super long...

froggy47

Is there a target temp. that must be attained for the heat cycle to happen?

Soloontario

Yes, I was aware of the lack of squirm as the tire wore down resulting in better overall grip. The magic part was that the rubber didn't get harder after a ton of heat cycles. Not sure that the RA-1 would be any faster than any of the Extreme Performance street rubber at the same tread depth (could well be a bit slower as I have never done back to back testing) but it would last a lot longer.

GrantB

I've been through probably 5 sets of R-S3s, and yes they do get slower as they age. I generally find the tires are noticeably faster the first two events I do on them. By the time they are down to about 2/32"s they get noticeably worse. When switching from nearly-corded R-S3s to a new set, I would generally pick up a second on an 80-second track. I have never run shaved R-S3s. I do have DAQ to back up these experiences.

I do not count heat cycles, as I believe that is an overly simplistic measurement of tire life. How long the tires sit after they've been cycled and how hot they get seem to be important variables as well.

I tend to drive very hard on cornering-intensive tracks, and have never "cycled out" a tire before it was corded. So if you're driving easier on tracks with more straights, YMMV.

Xian

In my experience, the compound *does* get harder. If you haven't already, try running a set of new, shaved RA1's after a set of worn down, old ones. The difference is pretty shocking.