On Wed, 9 Apr 2003, Paula J. Graffam wrote:
> Listers,
>
> I've got a set of Michelin redlines stacked in my garage with a LITTLE
> dry rot around the edges. I'm not sure how old they are but I really
> don't want to junk them since it might be possible to mount them back on
> again in the future WITHOUT the tubes. See previous discussion on the
> list.
>
> Question . . . once dry rot begins is it inevitable that the tires will
> become useless over time? Does dry rot spread like fungus? I've been
> riding on them for over three years (a hard ride at that) until I decided
> to put on a new set.
>
> Al Graffam CT. 74
I can address this topic...
The rubber in your tire is a compound of a whole bunch of stuff. The
material is fairly stable (meaning the chemical composition does not
change) until you heat-cyle the tire. Once you heat cycle any tire, an
outgassing process starts that is difficult if not impossible to stop.
Eventually, as certain materials outgas, the elasticity of the tire goes
away. This is generally when you start to see the little cracks on the
sidewall.
Now a lot of us play with this chemistry by spraying on all sorts of "goo"
to make the tires look better, or shine more or even to stay sticky for a
longer time. Without a phd in rubber science, it's pretty easy to see that
these compounds effect the tire too. TO the better? I have no idea. I do
suspect NOT because if you use some of these tire compounds the rubber
turns brown. I do not know what the brown stuff is, but it is probably
not good.
That said - there is a def. lifespan for all tire once you heat-cycle
them. Once you get beyond that lifespan, the tire is gone. That's that.
The Michelin X is also a steel belted tire. They were built when the steel
belts were constructed in an entirely different manner than they are now
(for example new tires encapsulate the steel for a longer life). I have
heard (directly from a Michelin tire engineer) that these old tires can
suffer dramatic belt failure because the steel belts RUST.
To be honest, when I'm at a car show and see a nice TR6 on what are
obviously old "original" Michelin X tires, I shudder trying not imagine
those things blowing up while the car is cruising down the highway at 65.
Yikes!
But I'll bet you can get some good money for them on eBay.
:-)
rml
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