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Old 08-15-2005, 07:34 AM   #1
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Default JACO Foam Durometer Numbers

Hi guys, I have a couple of things that are puzzling me about a pretty big lot of JACO tires I just picked up. 90% of these tires were new, out of the box, and while they arrived all in one bag (no original packaging), it was obvious that they were new. In this collection was supposed to be 12 pairs of pink front 12th scale tires, and a spattering of purple fronts as well.

So last night, I sat down to sort, measure and bag up all of the tires to store for the upcoming season. Because many of the tires had no label dots on them, I wanted to check them all with my duromter. What I found was downright confusing to me. My durometer is a MaxMod piece, and is calibrated correctly. The numbers I get on other tires are on, +/- 2 shore.

Going by a durometer number chart found in a JACO thread here on the forums, I got readings on these tires all over the map. From double pink to double purple, with a couple of pink, purple and even a pair HARDER than double purple in there, I got numbers all over the place. The rears that were in the package, which were all suppsed to be greys, saw only one pair in the grey number area.


Ok, two questions for you guys.


1) Does anyone have an accurate list of the JACO durometer shore numbers as compared to the "color dot" marking system, which I believe to be horribly inaccurate in matching tires (of the same brand).

2) If a table of tires was sitting in front of you, all of the same brand, would you disregard the color dot markings and re-mark them with your own durometer readings, knowing that there are definitely hardness differences between pairs? I know in my head that they should be remarked based on the actual numbers that I see, but I am wondering what some of the more experienced carpet guys would do.


Also, if a JACO white is supposedly a 28-30 shore, then what on earth is a tire that reads less than 25 shore?



Thanks,


doug
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Old 08-15-2005, 11:27 AM   #2
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If they don't have dots on them, be careful. They may not be ours. I could maybe tell by the way they are trued. Last year we skewed the whites and greys to the soft side as we were getting complaints that our rears were too firm. Whites should be around 25 and greys around 30. We did not update the site on this. Now everyone is complaining that they are too soft! Oh well. With regard to your fronts, since we don't make double purple 1/12 I'm not sure what is going on there. The MaxMod is good to compare tires relative to each other. However, if you have a bag full of tires with some undotted, don't rely on the durometer alone. I can tell you 3 or 4 tires that all durometer 30, but are completely different in their performance. If you want to send them to us (JACO) I will be glad to sort through them and redot them using our system. If there are any tires that are crazy off on numbers I will replace them (assuming they are ours). We do get variations in durometer readings from batch to batch and they will harden over time, but for the most part, our numbers should be very close to the range specified. By the way, we use a Type C Asker durometer (the same used by the factory and it is about $600). The MaxMod usually reads a little higher than ours, but again, it is a good device to compare tires in your box against other tires you may own.
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Old 08-15-2005, 11:36 AM   #3
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Thanks Jack, I'm pretty sure they are definitely Jaco tires, and I will PM you with who they were from. I may send them all to you to definitively test and mark them so I know what is what. The durometer numbers were kind of all over the place, but consistent at least with how they read, if that makes any sense. There were tires that read 40 and tires that read 37 and were very consistent throughout the bunch on how the numbers came off the durometer.

I may just send them to you to see if you can make heads or tails of them, and where I need to be with my chassis/tire setup.

I can't seem to find the jaco website, what is the URL?



THanks much,


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Old 08-15-2005, 11:43 AM   #4
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Oh, by the way, they didn't start out to be double purples, but they definitely were 5-6 shore above where the purples were reading. I found a chart somewhere in these forums that had double Ps listed at 45, so that's where I marked them.


Thanks,


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Old 08-15-2005, 01:29 PM   #5
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Quote:
Originally Posted by ApexSpeed
I can't seem to find the jaco website, what is the URL?
www.jacoracing.net
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Old 08-15-2005, 05:18 PM   #6
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Jack,

What are the compounds of the two stage 12th scale. I would like to use them for 12th stock on carpet. Which would be the best or are more for mod than stock. Didn't see any info on the website, but Tower and Stormer have them in their catalogs.

Thanks
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Old 08-15-2005, 07:24 PM   #7
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Website will be updated shortly before the start of the season. ( we are just waiitng for the photo's)


In 1/12 scale 2 stage we offer:

Fronts:

-Double Pink
-Purple

Rear:

Double Pink

With the 2 Stage tire you can get away with running a harder compound without giving up any traction, this allows the tire to wear longer.

Most people that tested in mod liked the Double Pink fronts and Double Pink rears.

Hope this helps.

Korgae

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Old 01-02-2006, 02:42 PM   #8
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Hi, i read in the Jaco site about the different compounts for 1/12 tires.
I found in Stormer a black compund, how do you rate this in comparison with the other in the site?

thanks
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Old 01-02-2006, 03:38 PM   #9
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korgae... has the 2 stages been used alot in stock 12th? if so what seems to be the hot ticket. and if not will there be new 2 stage sompounds coming out that might help stock 12th?
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Old 01-02-2006, 03:52 PM   #10
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My experience of this leads me to be very careful about grading tyres using durometers. In the main, people use scales that go from 0 to 100+ Shore, and this is not sufficiently accurate as you are only using the very lower part of the scale, 0 - 30.

Also, you are measuring across a curve, and this makes accurate readings even more difficult. I know drivers who have exactly the same problems you describe.

The Shore number is less important than the compound, so knowing the Shore rating is much less than half the answer you need! Greys and Pinks will measure pretty similar on the durometer you are using, but the track performance will be very different.

There is really no substitute for buying original equipment, using the coloured dot markers, and then keeping tyres together. Experience is the best guide to which compounds to use. HTH
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Old 01-02-2006, 04:10 PM   #11
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If you happen to read this post from the start it is a little misleading. The tires in question were team tires that were used for testing, thus the lack of dots and the large variation in durometer readings.
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