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Slick tire hardness by tire durometer

Old 10-13-17, 03:12 AM
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Slick tire hardness by tire durometer

Although this can't be show as how much grip level is . And tire will get much softer with heat on
But can used as study line of heat cycle
On different brand
All this two tire are brand new , test at same day , cold

Hankook Ventus TD are average 75-78

The Advan A050GS average 58-65

The advan A050M average 70-74

Advan A005 slick M average 70-73

Kumho S700 with 2 heat cycle 71-76
Attached Thumbnails Slick tire hardness by tire durometer-photo186.jpg   Slick tire hardness by tire durometer-photo682.jpg   Slick tire hardness by tire durometer-photo504.jpg   Slick tire hardness by tire durometer-photo774.jpg   Slick tire hardness by tire durometer-photo121.jpg  

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Old 10-13-17, 10:28 AM
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Which compound Hankook TD did you test?
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Old 10-14-17, 03:39 AM
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Originally Posted by blue tii
which compound hankook td did you test?
c70
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Old 10-14-17, 01:17 PM
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please try the test again when the tires are heat cycled.

we've been running hoosiers and we know they are done because when i go to take tire temps the probe won't go in them! its a bit odd because its a little before the driver says anything.

i think if you tested the hoosiers they would be in the same range as the tires above (~70), but after a couple weekends they would be the same harness as a rock
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Old 10-16-17, 01:00 AM
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Here are the Hoosier bias and radical
New but in storage for a while 2-3 year in dark room
Bias 75-80
Racial 73-79
And and worn out bias 77-82
I think Hoosier type of tire unlike Yokohama
Will get harder by time, so use it asap
Attached Thumbnails Slick tire hardness by tire durometer-photo238.jpg   Slick tire hardness by tire durometer-photo696.jpg   Slick tire hardness by tire durometer-photo754.jpg   Slick tire hardness by tire durometer-photo449.jpg  

Last edited by diyman25; 10-16-17 at 01:14 AM.
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Old 10-16-17, 01:09 AM
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Here are my A005 slick that I used for two race weekend about 50lap on 3km course
Tire get slightly harder compare to new one

A tip on tire
clean out ur slick before use it again
U can see those tire strip that stick on the surface of A005 is much harder then actual slick 77-80+
Attached Thumbnails Slick tire hardness by tire durometer-photo298.jpg   Slick tire hardness by tire durometer-photo938.jpg  

Last edited by diyman25; 10-16-17 at 01:13 AM.
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Old 10-26-17, 10:54 AM
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Remember that a tire with a shallow layer of tread compound will always read harder than one that is thicker because there is less rubber to deflect. So worn tires will always read harder than the same tires new, even if the compound is the same actual hardness.

Also, tires from different manufacturers or with different compounds are not the same when trying to evaluate which will have more grip. Sometimes a harder tire will actually give more grip depending on the track surface roughness or the tread chemistry.

So, even though a durometer reading is useful, don't read more into it than you have experience with.
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Old 11-01-17, 12:38 PM
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I have always used the thumb nail test on tires. Its now an unconscious habit with me and every race car I approach gets the thumb nail test on its tires. I have observed this behavior in lots of other racers too.

To parrot DaveW, durometer and thumb nail feel doesn't prove much. When I was a poor racer scrounging tires, I ended up with a set of used McCreary formula car tires for my Mustang. They were soft as all get out - A++++ on the thumb nail scale. In practice, mounted on my car for an autocross, they had absolutely no grip.

Knowing the real world performance of a tire and how that tire changes with heat cycles is the only way to predict a tire's behavior in my experience.
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Old 11-12-17, 10:50 AM
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Originally Posted by DaveW View Post
Remember that a tire with a shallow layer of tread compound will always read harder than one that is thicker because there is less rubber to deflect. So worn tires will always read harder than the same tires new, even if the compound is the same actual hardness.
What? No. Used tires always read harder because they are harder. A signficant percentage of tire wear (50-90%) happens because of evaporation. The rubber gets harder with age.

This is why passenger car tires seem to wear halfway very rapidly and then they stay half worn for another 40,000mi. Much of the early "wear" is actually rubber shrinkage, and the compound gets harder over time.

This is also why you shave new tires to competition depth instead of just using old ones.

Hell, it's why serious autocrossers will discard tires after a handful of runs because they are "aged out" even if they have a lot of rubber left.
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Old 11-12-17, 10:26 PM
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did you test the Michelin slicks ?
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Old 11-17-17, 03:55 PM
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Originally Posted by DaveW View Post
Remember that a tire with a shallow layer of tread compound will always read harder than one that is thicker because there is less rubber to deflect. So worn tires will always read harder than the same tires new, even if the compound is the same actual hardness....
Originally Posted by peejay View Post
What? No. Used tires always read harder because they are harder. A signficant percentage of tire wear (50-90%) happens because of evaporation. The rubber gets harder with age.

This is why passenger car tires seem to wear halfway very rapidly and then they stay half worn for another 40,000mi. Much of the early "wear" is actually rubber shrinkage, and the compound gets harder over time.

This is also why you shave new tires to competition depth instead of just using old ones.

Hell, it's why serious autocrossers will discard tires after a handful of runs because they are "aged out" even if they have a lot of rubber left.
You are correct about tires getting harder with age and use. Of course they do. I never said that they don't. Clarifying what I meant to emphasize is that the durometer relies on deflection of its pin to measure hardness, so if the tread layer is thinner, say 1/16" thick instead of 3/16", you WILL get a higher durometer reading just because of less tread thickness to deflect. So you have to be careful that you're not seeing that effect when you measure.

On the other hand, it may be an academic difference, because a thinner tread will not heat up as fast (or may not get to the proper temperature at all), so that, too, will affect grip.

As a side comment, in the rubber industry, durometer readings are always taken on a sample at least 1/4" thick so that sample thickness effects are minimized.

Last edited by DaveW; 11-18-17 at 08:46 AM. Reason: added last sentence
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Old 11-20-17, 08:51 AM
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Originally Posted by Alpine View Post
did you test the Michelin slicks ?
i did. you dont want to know the result....... Michelin might get faster lap time then yokohama slick
but once you use it. the grip level will fall from sky !!! the one i test is very hard. even with on track auction
the slick is still harder then noraml yokohama slick
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Old 11-20-17, 09:04 AM
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Originally Posted by DaveW View Post
You are correct about tires getting harder with age and use. Of course they do. I never said that they don't. Clarifying what I meant to emphasize is that the durometer relies on deflection of its pin to measure hardness, so if the tread layer is thinner, say 1/16" thick instead of 3/16", you WILL get a higher durometer reading just because of less tread thickness to deflect. So you have to be careful that you're not seeing that effect when you measure.

On the other hand, it may be an academic difference, because a thinner tread will not heat up as fast (or may not get to the proper temperature at all), so that, too, will affect grip.

As a side comment, in the rubber industry, durometer readings are always taken on a sample at least 1/4" thick so that sample thickness effects are minimized.

thats right. the thinner the rubber the harder it will measure
for example this A050 GS tires that i took off from my race car the center measure is less thread u can see in the pic is below wear bar , and what i measure is 15 harder on the shoulder. !!!
Attached Thumbnails Slick tire hardness by tire durometer-22448333_10155242051729005_1222757159757746864_n.jpg  
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Old 11-20-17, 08:28 PM
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So which one is the favorite slick?
Is Hoosier A7 really faster than the non-dot slicks?
I was abit surprised a dot-r is faster than real slicks, just wanted to confirm from users with experience.
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Old 11-21-17, 12:22 PM
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You would have to compare apples to apples-
Alpine
So which one is the favorite slick?
Is Hoosier A7 really faster than the non-dot slicks?
I was abit surprised a dot-r is faster than real slicks, just wanted to confirm from users with experience.


In autocross real Avon non-DOT formula car slicks in an auto-x/sprint/qualifying compound are faster than Hoosier A7.

If you are comparing some non-DOT Continental endurance slick to Hoosier A7 the A7 will be faster in an auto-x/sprint/qualifying situation.

You have to balance-
Tire grip to how fast they grease up.
How light they are to how durable they are (catastrophic failure).
With the variables of size and rules in the equation as well.

It has been said in back to back comparison with CP autocross cars going between non-DOT and A7s that the non-DOT bias ply slick advantage over A7s has shrunk to only tenths to .5 sec on a 60 second course!
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