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PostPosted: Thu Oct 11, 2012 6:32 pm 
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Joined: Tue May 23, 2006 4:33 am
Posts: 713
the green rubber used to be a different rubber compound in the pre-vulcanization days when the tread was still glued onto the casing. Nowadays it's molded into the tread and from the color bleeding you see at times it doesn't seem to be any different except for color. However, vulcanization per se isn't the end of tire curing. The actual heat and times used don't complete any curing process. They do help with the bonding of the tire to the casing, but that's all that the manufacturer is trying to do and because the casing is open at that point (in the case of tubulars of course) it happens very quickly. We've actually done durometer tests on tires to see whether storage improved or worsened tires and found that Corsa Evo CX's didn't get any better but also didn't get any worse for at least 3 years, Conti Competitions didn't get better and got worse in a measurable way starting about 16 months (after delivery from Conti), Evo Pave 320 tpi's got noticeably better for up to 9 months (90% achieved in 6 months) and so far have been stable, GP400S's were completely unchanged since they came out (i.e., very stable), EVO Pistas were impossible to test because the tread was so thin, but perception was that they improved a bit and then were very stable, and tests of Dugasts and FMBs were all over the place -- one tire got better, one tire got worse, etc., suggesting that there was little quality control. So I wouldn't just read past threads about why vulcanized tires don't need to age, and figure that one needs to pay attention to the tire model and to personal experience with them.


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PostPosted: Thu Oct 11, 2012 8:00 pm 
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Joined: Sun Jul 13, 2008 9:01 am
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i had the yellow road version a few years back. not a great tire super slick in rain and lifespan was very short i swear by continentals now


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Posted: Thu Oct 11, 2012 8:00 pm 


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PostPosted: Fri Oct 12, 2012 1:59 am 
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Joined: Tue May 03, 2005 2:20 am
Posts: 5773
Location: Belgium
Hi,

Quote:
Conti Competitions didn't get better and got worse in a measurable way starting about 16 months (after delivery from Conti),


Some tyres do no longer use natural rubber for the thread but use synthetic rubber instead. There probably still is some vulcanisation involved during the manufacturing of the tyre at some point or other though.
This may explain some of results of the hardness testing that 11.4 did.

Either way, lots of tyres do change even after they left the factory. Some for the better, others just get worse.
Some, like most of the traditionally made ones a la Veloflex, just get better and better as far as puncture resistance goes but there is an inevitable degradation (although not major) in rolling resistance.
Then of course, those traditonal tubulars and their clincher variants (aka "Open Tubulars as some call them) are put together by using glue.

Those definitely do benefit from "aging" if only to make sure the thread does not start slipping or lets go where it meets the sidewalls etc. These artifacts should not happen but it sometimes happens that the tubulars get shipped before the glue is fully cured....

@11.4 You don't happen to have durometer testresults on Veloflex or Challenge for instance?

Ciao, ;)

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Last edited by fdegrove on Fri Oct 12, 2012 12:15 pm, edited 1 time in total.

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PostPosted: Fri Oct 12, 2012 2:47 am 
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Joined: Tue May 23, 2006 4:33 am
Posts: 713
fdegrove wrote:
@11.4 You don't happen to have durometer testresults on Veloflex or Challenge for instance?

Ciao, ;)


I don't have the data with me but we did look at the Veloflex Record and the Criterium and one other (the predecessor to the Master, I believe). The Record was quite different from the others, possibly because it uses a different and finer casing and a different rubber in the tread. The Record got much better in terms of cut-propensity for about a year, and then didn't change (and still hadn't changed after about 4 years, and more recent tires purchased have shown the same characteristics). Interestingly, there was actually a drop in rolling resistance as the tire aged. It would seem that perhaps the softer uncured tread was squirming quite a bit and internally had some resistance that dissipated as the tire aged. The actual durometer changes were statistically insignificant, but the tire became much more cut resistant. In short, the perfect tire for aging.

The other two Veloflexes definitely hardened up (a tire after one year was perceptibly stiffer in the hand than a fresh one from the factory) and the durometer readings were statistically significant, but the tire still didn't pick up statistically significant rolling resistance. The only other tires that behaved the same were the Vittoria Evo Pista (which had so little tread to deal with) and more recently the Evo Crono seems to be developing the same way. That may be because the Evo Crono seems to have the same tread as the Evo Pista, just with a light cotton antipuncture strip underneath and an ever so slightly heavier casing. The Evo Crono is a great superlight tire and looks to be one that only improves with age, literally like a good wine.

If you want to age some tires, the ones our evidence pointed to were the Veloflex Record, the Evo Pista, and the Evo Crono. Almost every other tire we tested became more cut resistant, and durometer readings were significant, but only a couple, including the Evo Pave, improved without other downside issues. Contis seemed to be the worst, so just buy them and use them. We didn't test Challenges. In open clinchers we tested PR3's among others, and found they became a bit more cut resistant but not enough to justify aging them -- just ride them. Same advice for practically all other tires -- open and tubular -- except the three mentioned above. Other than those three, only Open Pave's aged even marginally in a way to justify doing so.

Note that these tests were on tires stored in cool, dark, humidity controlled, ozone free spaces. We did a few crude tests on tires that were simply mounted and ridden. Evo Paves came in for the most testing, and after a week on the bike they acted pretty much like tires aged for three months. Same for 4000S's and Evo Corsa II's in black. The best curing for some tires is just on the road.


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PostPosted: Fri Oct 12, 2012 1:09 pm 
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Joined: Tue May 03, 2005 2:20 am
Posts: 5773
Location: Belgium
Hi,

Marvelous. :D
At long last we now have it least some data to back up the subjective experiences.

Quote:
The best curing for some tires is just on the road.


I suppose that's also where they'd "deteriorate" the quickest as they are then exposed to aging agents such as ozone and U.V. rays....
Furthermore I'm also rather reluctant to call the aging process "vulcanisation" as this process involves heat. Maybe a better term would be "oxidation" for lack for a better term. (I'm pretty certain it's a chemical process involving more than just binding O molecules to other free molecules but still)

Either way, thanks for sharing. :beerchug:

Ciao, ;)

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