Anyone use a durometer to measure track tire life?

[RaceProEngineer]

Hi Chris,

I see your point about the durometer NOT being that valuable "at the track". I suppose I never tought about that problem, because we use ours on completely cold tires ONLY. I believe I posted the cold tires only suggestion in the other recent thread that dealt with the subject.

We have never tried using a durometer concurrently with our pyrometer, as you suggest, and you got me wondering why that is! After considering the question, I think of these instruments as having completely different purposes. Obviously, we use pyrometer readings to adjust suspension settings IN REAL TIME.

But the durometer is more of a static measurement of the tire's grip potential. Its true usefulness is in its ability to predict - not what the tire did in this session, but what it will do the next time out. (You also know all that.) It is my IMPRESSION that taking readings while the tire is still cooling will not render anything useful, because one can not see the effect of the "curing" that happens following that last heat cycle. Once the cool-down is complete, now you have something meaningful to measure.

Impossible to know for certain, but we are convinced that Dante "got robbed" of an SCCA win last season when I sent him out on tires that looked perfect, but that started to "go off" one-half way through the race. We are doing our best not to repeat the performance!

Ed

[cstreit]

Ed,

Gotcha. Well honestly I've had pretty good success just heat cycling tires out, but sometimes they go off "earlier than normal" which I suspect is what happend to your guy. Thing is, I don't think you can necessarily use a durometer to predict this. Lets take a hypothetical:

1. Tire Brand XYZ on a particular car usually heay cycles out at 12. You do a cold durometer reading prior to the weekend and all seems well.
2. Due to a combination of use, track, heat settings, etc... THIS SET of tires is only going to last 8-9 heat cycles.... Maybe simply because the side-switching schedule was missed.
3. You send out the driver at heat cycle 6 or 7 (well within your expected window of 12). At then end of this cycle, the tires are really "done" and will not last a long race. However since the tires have residual heat left in them from the morning session, they still show soft.
4. Halfway through the important session, the middle of the tire gets rock hard and goes off.

This has happened to me several times in the last two years. Haven't found a way to predict it. So when the chips are down, I go with the newest tires i have.

Now none of this is rocket science and certainly stating the obvious to you, but somebody in that situation you refer to made the decision to use those tires when they must have been getting "close" to their usual worst-case-scenario lifespan and the price was paid.... I have noticed that I have to religously swap sides on tires at the end of the day, and after every session once they are getting towards the end, or the outside tire will go off 3-4 cycles before their normal lifespan.

Bottom line, I'm not sure a durometer would help in this situation as my experience is the durometer says the tires are good, right up untill they aren't.