<VV> Tire life

[Jay Maechtlen]

On 1/21/2020 5:32 PM, Bryan Blackwell via VirtualVairs wrote:
> For those of you who wish to read further on tire life (in years), here are links to some studies on the subject from the folks who declared our Corvair safe:
>
> NHTSA Tire Aging Test Development Project Phase 1:
> https://one.nhtsa.gov/DOT/NHTSA/NRD/Multimedia/PDFs/Crash%20Avoidance/2009/811201.pdf
>
> NHTSA Tire Aging Test Development Project Phase 2:
> https://www.nhtsa.gov/DOT/NHTSA/NVS/Vehicle%20Research%20&%20Test%20Center%20(VRTC)/ca/capubs/811780.pdf

The accelerated aging test is interesting - note what they did -

"50 percent nitrogen gas and 50 percent oxygen gas (50%N2/50%O2) and 
aged in a circulating air oven for 3 or 5 weeks at 65°C. The fill gas 
was vented and refreshed weekly to maintain a sufficient supply of 
oxygen gas in the tire cavity to support oxidative aging."

That is  50% oxygen in the tires - not the 21% of standard atmosphere - 
and vented and refreshed weekly to keep that percentage up.

I don't see any references to actual tests of tires used on the road. I 
wonder how relevant this artificial aging of the inner tire is, when in 
service the oxygen content of the air in the tire will drop as oxidation 
takes place.  The failures of the inner surface and between layers could 
be heavily influenced by this.

If nothing else, don't run old tires underinflated or at the maximum 
rated loads for long periods of time!

Jay

>
> Personally in the DC area I go with 10 years from the sidewall date.  Since our Corvairs don't get a lot of miles, choosing to change them by age rather than tread depth seems to make sense, and some of our other tires (winter, trailer, etc.) have the same issue.
>
> BTW, if you don't know how to read date codes, I have a how to here:
> http://autoxer.skiblack.com/tires.html#age
>
> --Bryan
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-- 
Jay Maechtlen
SoCal
'61 2-dr modified w/fiberglass skin,
transverse 3.8 Buick V6 TH440T4 trans