I read a comment on an RV motorhome forum:
"I continue to read posts indicating that tires will calendar out, in 5 or 7 or even 10 years. After some searching I have yet to find a technical document regarding tire life expectancy. I'm not interested in sales brochures or salesmen guide lines. I'm looking for a document written by a subject matter expert in the tire manufacturing industry. IMO tire life is more a function of proper storage, inflation, maintenance, environment, and care. I believe a physical inspection by a tire professional is more reliable than an arbitrary date."
Maybe you can tell me, in hours, how long a gal of milk will stay "good". Since you know you can't answer that simple question why do you think the answer for a complex structure such as a tire age should be that simple. Do you think that all 27 basic components age at identical rates?