Anyone use a durometer to measure track tire life?

[moneymanager]

I know one or two of you do; I'm interested in what people think of the reliability of this method.

[RaceProEngineer]

Hoosier A6 longevity questions

Originally Posted by gulf911

Has anybody used a durometer to mechanically confirm heat cycled out? Can a durometer be used as an accurate gauge in this regard?

Is there an echo in here?

Ed

[moneymanager]

Yup. And as I recall no one answered you either .

[campbellcj]

I just got one but have not started using it yet (my car has been down for several months). Does that count?

I'll be glad to share anything I learn but it will be a while. I'm running Hoosier R6's.

[moneymanager]

Ed, I repeated Gulf 911's question then mistakenly attributed it to you. You were the one person in the original thread I think who had actually reported using the durometer. I was and still am trying to see if anyone else would chime in with data. The durometer seems to me the one thing that might bring a bit of science to what is otherwise a topic addressed mostly in anecdotes.
Chris, thanks. We await your data!

[RaceProEngineer]

Hi Jim,

That Hoosier A6 thread was one I started, and then it morphed into the discussion of other things, the durometer included.

This topic deserves its own thread. I, too, hope others will join in with how they might be using these devices, and their findings.

What we have discovered, as I mentioned in the other thread, is that durometers are kind of relative, rather than absolute. So, like a leak-down tester, its numbers are consistant IN THAT DEVICE, but do not necessarily equate to values in another leak-down tester.

Thus, here is the caution about being a little more scientific: Someone may post that "Goodyear RSs are 'used up' when the durometer reads 91." While that poster may be absolutely rigorus is arriving at those findings, that 91 reading applies only to his durometer.

Ed

[moneymanager]

Ed, I understand. But if we knew that several people thought there tires were gone when their readings went up 30%, I think we might have something useful. Probably there isn't much of a pattern, even of my limited kind, or all the books would be explaining how to use the data! Jim

[Flieger]

Can't you calibrate a durometer? How do they work? Some sort of indenter like a hardness tester?

[moneymanager]

Durometer is a hardness tester, albeit limited to rubber, plastic and the like. You can get one for $60, or $1000. I'm going to guess the expensive ones can be calibrated, but $1000 will get a new set of tires!

[moneymanager]

Ed,
In your experience does using the same durometer over time give you comparable results... ie does an 88 on your meter always mean that tire is near dead and a 91 that the tire is shot?
Jim

[naparsei]

Wouldn't "used up" be a function of a lot of things? Some tracks in my region reward harder tires and less treaded (nearly bald) tires, and some like softer, more treaded tires. I am not trying to be a killjoy - I too would a scientific solution. Just asking to learn.

[RichardNew]

A column I did last year on tire tools.

Richard Newton
Newton's Law

[RaceProEngineer]

Originally Posted by moneymanager

Ed,
In your experience does using the same durometer over time give you comparable results... ie does an 88 on your meter always mean that tire is near dead and a 91 that the tire is shot?
Jim

Correct, Jim,

All that we have seen are consistent WITHIN THEMSELVES. They will reliablly and consistantly show the degradation of a given tire over time, so I trust their "percentages". Further the same tire, measured several times while not being run will always read the same. And even further, several brand new Hoosier 45 compound slicks will all, and always, read the same as long as none were aged on the shelf.

As I mentioned in the older thread, across types and brands, air will always read ZERO hardness, while steel will always read ONE HUNDRED. But a 75 reading on one durometer will not necessarily read exactly the same on another durometer. In short, it is safest to make your measirements, and plot trends, using the self-same instrument.

Ed

[RaceProEngineer]

Originally Posted by naparsei

Wouldn't "used up" be a function of a lot of things? Some tracks in my region reward harder tires and less treaded (nearly bald) tires, and some like softer, more treaded tires. I am not trying to be a killjoy - I too would a scientific solution. Just asking to learn.

Not to be smart here, but we are unaware on ANY road race tracks that "reward" tires with treads.

Plyability of the "rubber" compound typically equates to mechanical grip, which in turn has a direct effect on performance. Unless one is running a 4000 pound car, or the ambient temperature in 95+, a softer surace tire is going to be faster. When the tire's surface becomes hard, it is used up.

Of course, rain tires are a completely different subject, and achieve their grip in a more complex fashion.

Ed

[winders]

Originally Posted by RichardNew

A column I did last year on tire tools.

Richard Newton
Newton's Law

Richard,

Your column is a bit on the superficial side. It doesn't go into any depth at all and doesn't really add anything to this discussion.

What is needed is an in depth discussion on what methodology to employ to get useful data and how to interpret the readings provided by a durometer. This would allow drivers to make informed decisions on tire usability.

It would be great to be able to use a durometer to tell you your tires are toast instead of having to find out, too late, in a session. What would be even better is to have the durometer tell you the tires are good for more use when you were going to toss them.

Scott

[winders]

Originally Posted by RaceProEngineer

Not to be smart here, but we are unaware on ANY road race tracks that "reward" tires with treads.

Ed,

You are spot on. On a hard surface, treads are never a good thing in the dry. Treads mean less rubber contact per square inch of tire contact patch. Treaded tires overheat faster due to less contact area and tread squirm.

Scott

[KTL]

I recently bought a pyrometer and a durometer because i'm tired of winging it and going by feel. I'll be using the durometer on a regular basis and will log my measurements in a spreadsheet. I figure it has to be a better way to track my tire's useable life instead of by my inconsistent lap times........ :P

[RaceProEngineer]

Kevin,

Suggestion: When doing your logging of readings, it is a very good idea to connect each reading with "comments" or a memo, like
55 ** Purchased brand new
66 ** After 20 minute qualifying session
68 ** Only 3-lap heat cycle due to red flag
70 ** After storing for the winter
78 ** After 30 minute sprint race
82 ** 10 minute practice session - starting to "drop off"
etc.

Then, from your spread sheet, you can predict how your next set of these same tires will behave. You will also have an invaluable base from which to evaluate other track tires.

Ed

[cstreit]

Here's the issue I've had Ed... Unless I measure tires when they are always the same temperature, I'm getting inconsistent readings...

IE, the same tire 20 minutes off the track reads 55 and later that evening reads 65 or 70.... So I don' t think the durometer is all that useful AT THE TRACK.

...and frankly that's when I need it most. I know some tires are getting close, but do I dismount them (cause this usually precedes throwing them on the heap) or keep them...

So there are TWO factors to be measured otherwise the discussion is really moot.

[J Richard]

I've seen some pro tire sheets, the tires are checked before the session, durometer in three places across the tread, and temps across the tread, cold on the way out, then in from a hot session. along with pressures. All three are interrelated. It would be easy then to correlate your fastest lap times with the hardness, temp and pressures of the tires. Most of this seems to get used for compound selection, as they pretty much trash them when it makes sense from a race strategy. I have one I've played with a few times, on old tires when I wasn't sure if they had gotten hard over time comparing to new, but then they do soften up on the track. I think you have to be more consistent to have any reliable/useable data...