Between the rising price of diesel fuel and the continuous stream of increases from new tire and retread manufacturers, the last thing that fleets need is an arbitrary age restriction on casings. I use the word “arbitrary” because there is still no irrefutable scientific data that establishes a set limit on how long a tire can remain in service. Most importantly, the relationship between casing age and performance depends largely on the application and the level of inflation pressure maintenance. That being said, there are still some facts about tire aging that every fleet must understand to prevent tire costs from rising unnecessarily.
Depending on the make and the model, most truck tire warranties are between five and seven years from the date of manufacture or date of purchase. Some of the casing warranties also include a minimum number of retreads, but they're only valid if tire and retread share the same name. Put a Brand X retread on a Brand Z casing and the retread guaranty vanishes faster than fuel mileage at 70 mph. As long as the fleet has proof of purchase, the five- to seven-year period starts from that date, so recording the date codes on every invoice is a good practice that every fleet should adopt immediately.
Speaking of date codes, the company that sells the fleet any number of tires is required by law to supply the Dept. of Transportation with the entire tire identification number(s) on a form that can be mailed to register the tire(s) so the fleet can be notified in the event of a recall. Truck tires are rarely, if ever, recalled, so too many tire dealers neglect to provide that information to the fleet because it's never been a problem. Rather than wait for it to become one, fleets should begin asking for the tire registration information at every purchase so there won't be any questions should the first major truck tire recall occur in the near future.
A prime time news program recently “exposed” the dangers of tire aging in a totally one-sided report that compared date codes on tires to other products that decompose with age. The premise is ridiculous because one of the driving forces behind tire recycling is that scrap tires will occupy the same amount of landfill space for hundreds, if not thousands, of years. That being said, improperly stored tires will experience a condition known as ozone cracking that strongly resembles the infamous “dry rot” that accompanies older tires.
As a tire ages, the surfaces are constantly attacked by ultraviolet rays and sources of ozone that make the tire less pliable. That's why a new tire that sits in the sun too long develops severe ozone cracking. Tire manufacturers can counteract most of these “attacks” with chemicals that keep the rubber pliable as long as it is exercised on a regular basis. During a period where a lot of equipment may be sitting idle, it's important to get the parked trucks out on the road from time to time so the tires don't dry out. It's equally important to keep spare tires out of the elements.
In theory, the age of a casing should not matter as long as the tire has been properly inflated and maintained. At a point when fleets should be doing everything they can to extend the life of a casing, our litigious society is making it difficult. Every tire program must find balance between age and performance by working with new tire and retread manufacturers to find the range that works best for each application.