Originally Posted by Busa Dave
...designed it flexes more than it should in a smaller area of the sidewall. This will cause a catastrophic failure if it is allowed to go on long enough. Really evident in older tires that have had embrittlement set in which in many cases is not readily apparent from the outside of the tire.
I will not run tires that are more than for years old nor will allow new tires that are over a year old to be installed on my vehicles. Also use nitrogen as a fill.
In short if you are running tires more than 5 years old you are fighting the odds. Uncle will not use a aircraft tire over 3 years old. Always Always look at the DOT number to determine the age of the tire. Heat cycles also play into this---mileage is exclusive when it come to judging tire life...
I generally dont believe posts like these simply because the money/time factor involved and the overall obtuseness of the supposition. Your 4 year tire rule is utterly absurd and if all you do is worry about tire age then you have a very, very, very uneventful life. Id wager you dont have Uncle Sams unlimited deep pockets, either. Pretty sure even the most expensive RV costs a fraction of a passenger or military aircraft. To apply the same maintenance schedules or benchmarks to pedestrian vehicles is fruitless and expensive and pure fantasy. I have very detail organized mechanic friends and even they want every mile out of the rubber wrapped around their wheels (and then some) even if they are 20+ years old vintage aged tires.
In a typical week I drive 3-5 different vehicles. Mostly rentals but some fleet, & loaners. I have never taken the time to date code the tires or even check the air pressure. I'm more mechanically inclined than most.
Im sure as hell not putting new tires on every vehicle my behind gets into.
Your "empirical" research has so many holes in it that it smells like cheese. But it makes for nice discussion fodder.
FYI... my coach has 9yr old michelins and most will see their 10th year of service in 2015. I figured out the time & cost of roadside service is cheaper than going to local shops that want to charge $150 more per tire for a casual appointment.