From: none@none.com99   
      
   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.  O3 also   
   contributes to the break down of rubbers and is more reactive.  Then I   
   looked at concentrations per a few other references.  They say CO2 is   
   present at ground level from 300 to 900 PPM (million) where as O3 is   
   typically present at 20-30 PPB (billion).   
      
   As to whether the difference in available molecules makes a real   
   difference in which has more net affect I do not know, but the numbers   
   do make you think.   
      
   I recall now where I first ran across the reference to CO2 and its   
   reactivity with rubbers.  I don't recall exactly who it was (could have   
   been Bob Sterne), but it was in regards to tuning, building, and   
   repairing airguns.  Admittedly air can be quite distressed in a spring   
   piston gun generating enough sudden compression to detonate oils or in a   
   PCP gun where air can be stored at pressures as high as 4500PSI.  Over   
   300 bar for the metric crowd.   
      
   I'm not saying I was right and you were wrong.  Not at all.  I could   
   very well be wrong still.  My "expertise" with material science is   
   limited to rote memory and blue collar experience.  I'm just stating it   
   might not be as cut and dried as as it seems.  I would argue in full on   
   flat Earther fashion... "Nothing is ever totally settled science."  LOL.   
      
   --   
   Bob La Londe   
   CNC Molds N Stuff   
      
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