Hey guys, think of it this way. When a coolant hose fails, is there always an external bubble to warn you ? No matter how much rubber protectant you use, you are only treating what you can see on the outside. The hose like tires are made from several layers of materials. A common hose failure is much like a tire failure. It is normally caused by a separation between the layers of the hose/tire. If you are lucky you will get some warning in the form of a visible bubble. That is if you routinely inspect your tires, belts and hoses. In a hose, heat and pressure can accelerate the failure.
In a tire, heat, tire pressure (or lack of) proper pressure, and the load of the weight being carried and the speed (centrifugal forces try to pull tread off)of the tires rotation all act on the tire. They are much more complex than most think. Tires are constructed of many different materials custom mixed according to the tires application. All Weather, M&S, Performance, OTR, speed ratings etc...Once the tire is assembled and cooked (vulcanized) in its mold the clock starts to tick. The clock runs at different speeds based on use and storage. A wrapped tire, stored in a cool, dark, environment ( sounds like storing medications and food ) will have an extended life compared to a tire sitting on a tire rack, trunk or on the vehicle itself. All materials have a designed life expectancy, that is the major function of a date code. A tire can look perfect on the outside and have a flaw or damage to the inner liner caused by faulty materials or workmanship. Impact bruise on liner from pothole, rail road track crossing etc... Here is the long and short of this thread. Always err on the side of safety. Unless the tire is for display or you are just moving the car at less than 30 mph or so and it is more than 5 years old according to the date code, don't risk it. A tire failure at hi-way speeds is not only dangerous for you an others, but can cause extensive damage to your vehicle. Tire cost $ 200. for a good quality tire, Quarter panel, fender, paint etc.. damage to the car $$$$ Hospital... No matter who tells you that it will be fine, there are no guarantees. I am retired from Bridgestone/Firestone as a tire store manager and worked the Ford Explorer/Firestone Radial ATX recalls. We learned a lot first hand about the effects of the tires age, proper inflation, excess load, tire inspections...Be Safe Although not widely reported, those in the industry also knew about silent recalls from Goodyear and other tire manufacturers that were not as large but just as dangerous.