billwill wrote:Reading the two articles together the main benefit of using nitrogen as filler gas would not be the slower leakage, but the oxygen avoidance should let the rubber last longer before oxidising -> hardening -> cracking.
The earlier article seems to find that the tyre aging problem is mostly caused by the high pressure oxygen part of the air in the tyre.
Can't say I've ever taken a used tyre off of any vehicle and seen any interior degradation that's given me cause for concern. I replaced a tyre on a motorcycle a few months ago because of external cracks but the interior looked fine. That tyre dated from 1976.
I would have thought that it was the exterior that had most oxygen exposure. The interior gets pumped up but the oxygen concentration isn't "orders of magnitude higher", it's maybe two or three times higher and, apart from diffusion, not replaced (unless you get a flat). The outside gets constantly bombarded with not only oxygen but also ultra violet light (ok, not so much in the UK
) particularly in the sunshine states mentioned.
I wonder how much of the difference between the car companies stance on tyre life ("older than six years should only be used in an emergency") and the Rubber Association ("all tyres should be replaced 10 years from manufacturing date") is down to performance rather than safety.
The tyres on my Elan are coming up to 10yrs old and will get replaced before it does any serious miles this year but I've inspected all of them recently and there's no cracking or visible degradation anywhere on them that I can see - probably because they've spent a good part of that time in the dark in my garage. I'll be replacing them for "performance" reasons but if I was only puttering down to the supermarket (like my next door neighbour does in his 10yr old car) I don't think I'd give them a second thought.