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914World.com _ The Paddock _ Tire rubber hardness

Posted by: Joe Ricard Oct 18 2007, 07:35 AM

http://cgi.ebay.com/NEW-LONGARCE-TIRE-DUROMETER-W-POUCH-HARNESS- GAUGE_W0QQitemZ320170818884QQihZ011QQcategoryZ7318QQssPageNameZWDVWQQrdZ1QQcmdZV
iewItem

There is a guy selling a mess of tires and stated durometer hardness as a method of how fresh the tires were. or the degree of how gone they are.

Might have to get me one of these just because I am a gadget nut when it comes to my race car.

Posted by: woobn8r Oct 18 2007, 09:10 AM

I have a Durometer.
It's a good tool, but it only adds a piece to the puzzle. You shouldnn't for example, purchase a particular brand of tire for autoX based on how soft the rubber is...the tire may be too greasy...or need heat cycling, etc. There are many other factors in tire selection (as you already know).

At work we use them for checking the consistancy of tread rubber as tires are made all over the world now and humidity is a HUGE factor in the curing of tires...not all companies are as good as the US or Japanease plants when it comes to control systems.

If you use it religously, and build a good database you will be able to learn some interesting facts about your particular racing application and have more ammunition when it comes time to make decisions.

Posted by: Joe Ricard Oct 18 2007, 10:06 AM

Yup, I have built a pretty good base of car set up # runs on a tire. Temps that the tire got up to. and my opinion of the grip that was available on that particular surface.

I would be curious how the durometer measurement correlated to the grip vs. # runs and temp.

One thing I have found is new tires grip so much that stiffer springs are required. as they get to half life and have less grip springs up to 100 pounds less work better.

Posted by: jhadler Oct 18 2007, 11:09 AM

Joe,

The durometer readings are not going to give you an accurate absolute number. They're better for relative measurements. Like, charting how a given tire ages over x number of runs. Always measure in the same conditions, and the same manner to get the best results.

-Josh2

Posted by: Brett W Oct 21 2007, 12:29 PM

I use one. Its useful to track age and degradation of race tires. Not as important for overall tire selection but it helps use tires longer. Laptimes are pretty much the way to judge the useful life of tires.