There a couple of other good threads in detailing covering this topic - of special note in regard to Armour-All
Re: What do you use on your vehicles?
« Reply #92 on: April 11, 2007, 04:23:20 PM » Quote
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Re: Armour-All on your tires--the details:
Here is a writeup from Larry Reynolds of Car Care Specialties, Inc, Saddle Brook, NJ, 201-796-8300,
carcaresp@aol.com during a recent PCA workshop covering concour tips for Porsche owners:
There are two main degrading agents that attack tires. They are UV light waves and ozone. Both of these attack the long hydrocarbon chains of the rubber and by breaking these bonds, shorten the molecules with resulting loss
of elasticity and other problems. Tire manufacturers add two primary sacraficial protectants to the rubber. To protect against UV, they add carbon black. This is why tires don't come in designer colors to match your paint.
The carbon black will turn white/gray as it absorbs the UV and dissipates the energy as heat. Thus the basis of rubber parts turning gray as they age. To protect against ozone, tire manufacturers add a wax-based sacraficial
protectant. The ozone attacks the wax and depletes it. As the tire rolls, additional wax is forced to the surface of the tire. This is referred to as "blooming". This blooming refreshes the surface wax protectant. A tire that
has not been flexed will have the wax depleted by the ozone and thus begin to degrade and suffer "dry rot". The silicone oil in Armour All et Al may actually dissolve the wax and be the cause of premature tire sidewall cracking/failure. In conclusion, any tire dressing should contain a UV protectant to bolster the efforts of the carbon black and not contain any silicone.[/color]
Probably more than you wanted, but it sure explains it well.