From: peter@tsto.co.uk   
      
   On 14/11/2024 19:31, Bob La Londe wrote:   
   > On 11/13/2024 4:58 PM, Jim Wilkins wrote:   
   >> "Bob La Londe"  wrote in message news:vh38u5$2dg8a$2@dont-email.me...   
   >>   
   >> On 11/13/2024 3:09 PM, Snag wrote:   
   >>   
   >>>    I thought it was exposure to sunlight/UV that caused most of the   
   >>> sidewall degradation ... or are those aftermarket tire covers (in   
   >>> particular for RV's and campers) just another scam ?   
   >>   
   >>   
   >> Yeah I don't know for sure.  UV is certainly capable of damaging a lot   
   >> of things.  I do know CO2 is an issue with some rubbers.  I was told   
   >> by... well somebody... that tires were among them.   
   >>   
   >   
   > Nobody likes to be wrong, so I did some look ups.   
   >   
   > CO2 is said to contribute to the breakdown of rubber on several sites.   
   > Some say "distressed" CO2 and others just generically say CO2.   
      
   I have no idea what "distressed" CO2 is, but CO2 dissolves in tyre   
   rubber, kind-of. It seeps into spaces between the molecules in the   
   rubber, and can seep through the rubber. This doesn't normally do much   
   damage to the rubber, but because of this seepage a tyre filled with CO2   
   will deflate quicker than a tyre filled with air.   
      
   That said, rubber in high pressure CO2 will absorb more CO2 - and if the   
   pressure is suddenly released, as in a CO2 gun, the CO2 can bubble out,   
   damaging the rubber, perhaps severely.   
      
   Another thing CO2 does is actually react with rubber, which can cause   
   damage. However the amount of CO2 in normal air isn't likely to do much   
   harm to car tyres - the normal oxygen in air will probably do more   
   damage, long term - but it could well damage rubber in CO2 guns and   
   airguns.   
      
   An aside, people put lampblack (carbon) in rubber for several reasons,   
   but a major one is to slow the reaction with oxygen in the air. The   
   oxygen still reacts, but (somewhere between greatly simplified and   
   lies-to-children) reacts with the lampblack instead of the rubber...   
   producing CO2, which permeates out to the atmosphere... But overall, the   
   rubber lasts longer.   
      
   Rubber should not be used to seal CO2 long-term, especially under high   
   pressure.   
      
      
   UV and O3 are very different animals!! Both will aggressively attack   
   rubber. And almost anything else, including humans.   
      
   Peter Fairbrother   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)