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Tire talk - durometers: Shore A vs. Shore O


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#1 James Grandi

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Posted 12 June 2017 - 11:43 AM

So! Here is a little bit of info for those who like to play with durometers - and spend money (unnecessarily in this case).

Left is a Shore 'A' scale durometer, bought it right off the parts truck at Stafford Motor Speedway in CT (1/2 mile oval).

Right is a shore 'O' scale durometer bought from an R/C shop.

Tested 4fourdifferent types of tire in three different spots (Thunder medium, HVR soft Wonder, JK small hub Wonder, Kelly Retro ). They all pretty much came out in the same manner, with a 1 to 2 point difference in reading at the most. Average them out, they're basically the same.

The lesson? Just because it's supposed to be better, doesn't mean it actually is LOL.

 

IMG_0072.JPG


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#2 gotboostedvr6

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Posted 12 June 2017 - 12:11 PM

What about shore 00?

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#3 James Grandi

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Posted 12 June 2017 - 12:19 PM

If you wanna buy one, by all means, measure away and post your results.


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#4 gotboostedvr6

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Posted 12 June 2017 - 12:20 PM

Material thickness will affect results dramatically.


Those who work for a living are being quickly overwhelmed by those who vote for a living.

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#5 Garry S

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Posted 12 June 2017 - 12:40 PM

Shore Scales "A" and "O" use the same spring force, but a different point configuration.  
 
Shore durometer
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#6 James Grandi

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Posted 12 June 2017 - 12:48 PM

Dennis Samson just explained the same thing to me on Facebook - I incorrectly assumed they used different calibrated springs.

As it turns out, it seems the modification I made to the Type A to make it useable for our tires inherently turned it into one that gives the same/similar readings as a Type O.
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#7 Half Fast

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Posted 12 June 2017 - 12:53 PM

It seems to me that the actual numbers are meaningless, except for comparison purposes to determine the relative hardness of your sets of tires.
 
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#8 Racer36

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Posted 12 June 2017 - 01:30 PM

I have an Intercomp Shore A and the Longacre R/C one as well. They read about four points different. I had hoped the rounded end would eliminate false readings with big hub tires, but nope.

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#9 Cap Henry

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Posted 12 June 2017 - 07:02 PM

Durometer readings, in slot cars, are only useful for that user. With the way our tires are, it makes such a huge difference on how much pressure is applied, if you push it straight down or roll it into the tire. Great tool for comparing your own tires, but not very accurate from user to user.

I durometer all my tires for big races with move-ups so that if I move up and need to change tires I know what's the same as what I'm running or what's harder/softer if I need to adjust.


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#10 Steve Deiters

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Posted 14 June 2017 - 09:47 AM

I see different  terms classifying durometers on Amazon -"Type A" and "Type D" or...

 

Any recommendations which is best suited for slot car tires?

 

Any brand preferences? Digital or dial? Brand?

 

Trying to make an informed choice on one of these.



#11 Racer36

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Posted 14 June 2017 - 10:19 AM

Steve,

 

Shore A seems to be the best and most common unit for slot or R/C tires.


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#12 SpeedyNH

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Posted 19 June 2017 - 06:00 PM

I've used mine for years, mostly as a curiosity.  I sure am glad to see these differences explained, thanks! 

-and with mine, it's always been obvious to me that taking a good reading was mostly dependent on having a sufficient thickness of the rubber.

speedy


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#13 Zippity

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Posted 19 June 2017 - 06:07 PM

Surely that regardless of which class of Durometer you possess, the critical thing is getting a constant reading between hard and soft?

 

Who cares what the numbers read.

 

Just as long as I can obtain a range of measurements, my Durometer is doing its job :)

 

Yes?


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#14 Racer36

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Posted 20 June 2017 - 07:44 AM

Absolutely Zip.

 Anyone with an eye and an anus can figure out that there will be variances between durometers just based on production tolerances.

The idea is to get a feel for what works on track and use the durometer to fine tune from there.

Easy Peasey!

I used it in 1:1 racing, kart racing and now slots, all with good success.


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