911GT3

I want a more objective way to determine when my tires are "heat-cycled" out other than when they just seem to be slippery. There are too many other variables like humidity, temperature, how much rubber is on the track, etc. So I bought an inexpensive durometer. I was thinking of measuring the hardness at the beginning of each track day, and keeping a log. Is there an advantage to measuring when warm, cold, hot, ?

NJ-GT

durometer to be used on cold tires. Measure when new, measure when old, and use the gauge to determine life at a given time.

I use heat cycles instead, record them after the track event, including miles on odometer, sessions length (from data acquisition), temperatures. My durometer has stayed unused for more than 3 years.

911GT3

Thank you. I record heat cycles as well, just wanted another piece of data for tire life. Maybe I will be all hyped on it for awhile, and then my durometer will sit right next to yours unused! Thanks again.

911GT3

test post

markus_t19

maybe a dumb question but what exactly constitutes a heat cycle?

on a track: each session is typically one HC?

and off track when "not going slow"

NJ-GT

Going from cold tire temperatures, to 130 degrees or more tire temperatures.

Each track session is one heat cycle. A 20 minutes track session is 1HC, a 60 minutes track session is 1HC (with more wear on the tread). A track session under heavy rain won't generate a heat cycle.

A fast drive around Canyon roads can put 1 HC (or more if you make stops to have lunch or have coffee). Even driving on a highway on hot weather at 65 mph can put 1 HC.

With my use, my Hoosier A6 are good for 8HC. Slicks are good for 8HC, some are good for 4HC, some are good for 2HC. R6 are good for 16HC. Shaved RA1 16HC. R888 16HC. MPSC 24HC. Trofeo: no idea yet. RE-11 1000HC.

911GT3

I seem to get about 25 heat cycles on my MPSCs as well. Then they seem to by harder and slippery. While they cost more, one gets more HCs from them, ..., and I hate to use this word 'cause it seems inappropriate, ..., they seem to be a bargain. (?)

markus_t19

Fantastic- that was the information i was after. Very helpful to me as i just getting my 3rd set of MPSCs and another piece to copy&paste into my reference file containing Best-of-RL snippets of information for future reference (after converting 130 F to 55 Celsius that is ) - just realise many entries in there from Rad- BIG thank you.

So driving on the Ring this could mean:
- as many as 20 HC in just one day eg in the sport&auto sessions (which I will do next Monday/Tuesday) because there is often a 5-10 minutes wait between each lap
- just 3 HC on track days when i may do 3 long(1 hour plus) stints to practice for VLN

NJ-GT

I carry 4 tire bags that work as tire warmers for autocross. I put them on if there is too much wait in between runs (sometimes 25 minutes), this keeps the tire hot (sticky) and avoid a 2nd HC on a 2nd run.

5-10 minutes is not enough to cool down a tire from a track session, unless outside temperature are cold, in which case the exterior surface will take another heat cycle, but this surface will wear out rather quick. A good safe average is each 100 miles of track driving consumes roughly 1/32" of tread on the sticky race compound tires (Hoosier R6/A6, BFG R1, Kumho V710).

Check the tire temperature before going back again on track, don't use a surface (infrared) gauge, use a needle type gauge like the ones sold by LongAcre,

Izzone

I use a durometer on RA1 all the time

Pretty accurate to see when the tread is gone and you are driving on carcus