|Reference . - SDC Forum #105406|
Bill Ozzard, British Columbia - March 31, 2018
Firstly, lets remember that the construction and materials have changed immensely. Bias ply became bias belted, nylon gave way to rayon and other polyester materials and ultimately then radial construction became the norm with steel belted tires as well as kevlar for belt support and strength. Our original tires from 60+ years ago were mostly made with real rubber. These tires were supported from the inside with very robust and forgiving tubes and liners.
Now most tires have very little rubber, are of tubeless construction and are mostly made from synthetic materials which are very susceptible to breakdown from ozone, temperature and sunlight. We used to receive letters from Michelin, Goodyear, Yokohama, Toyo, Bridgestone and several other major manufacturers requesting us to not press a tire into service if we knew the tire to be over six(6) years of age. There is a lot of lee way here as the manufacturers are covering their own butts in this age of litigation with absolutely no one wanting to take responsibility for their own lives. Modern tires deteriorate from the inside out so mostly it is near impossible to foresee a tires' impending demise unless it is physically separating and the tread is distorted.
Another factor is where the tires are being used. There is no way Bob in Phoenix will have a tire deliver the same range of service that Rich in Washington state or Gary in the northeast would receive. Heat is a killer. Those living in snow zones also usually have two sets of tires which greatly extend all 8 of the tire's longevity and performance. All 8 will also be rotated twice a year which also helps in longevity and smooth performance.
Remember the Ford Explorer/Firestone fiasco back in the 90's. The initial failures were from the high heat areas of the country such as Arizona, Texas and California where not just the ambient temperatures were high, but also speed limits as well which create more flex and thus higher than normal temperatures in the tires themselves. Part of the failure was due to Ford trying to get the ride quality acceptable in an otherwise truck chassis by labeling the door decal ratings to 26 PSI. It matters not what brand of tire subjected to those initial low pressures, normal human neglect(most cars' tires are usually approximately 8-10 psi UNDER the recommended pressures) will inevitably lead to failure with extreme flex and subsequent temperature increase. We in this forum are most probably more anal about our tires' pressure and condition than the average car hating individual who sees a car as a simple device to move one around.
I carry a laser temperature gun and when stopping for fuel on a long trip, I shoot each tire for a temperature reading. It hardly matters what temperature they are at, but rather the differential between the tires. For example, if you have just come off a 70+ mile per hour run for hours on end, all the tires should be running at fairly consistent albeit somewhat higher than normal temperatures and pressures. If one is considerably higher than the others, it is showing that it may have picked up a nail or in the case of this conversation, is starting to separate from age or normal degradation which causes excessive flexing of the tire, and thus higher pressure AND temperature.
Like Gunslinger, my '83 Avanti rarely gets driven but last year while travelling to our local chapter meet, a discernible vibration was being transmitted from the otherwise great looking Michelins which I know is a factor of age degradation rather than obvious tread wear out.
To be safe to both our well beings as well as our wallets I recommend replacing your tires every ten(10) years to err on the side of caution and safety. I hope this long winded explanation assists some of you.