I know we have kicked this can over and over but I stumbled onto something at the Discount Tire Direct web site. Buried into their FAQ regarding trailer tires, which in total is fairly interesting was this sentence.
- Time and the elements weaken a trailer tire.
- In approximately 3 years, roughly one third of the tire's strength is gone.
- Three to five years is the projected life of a normal trailer tire.
That note about the tire's strength is really interesting. I just wonder if one could project how that relates to the load bearing capacity of a tire. As I noted in a different thread I've now have had 3 ST tires (1 D rated and 2 E rated) fail due to belt slippage or broken belts. All three have failed in their 3rd year of use.
Prior to owning my Airstream, I pulled a 1982 21' tandem axle Hi-Lo travel trailer for 14 years and was bought new. Typically it carried no water load and I replaced tires 3 times in its life. I was pretty naive regarding tires and quite honestly to this date I can't remember if the tires were ST rated or were passenger tires. I know the last set of tires were radials, the prior two sets were not. My only tire failure in that 14 year period was my own error in moving the trailer to my new home in the dead of winter. Instead of checking inflation I just towed it to my new home which was about 4 miles from where I was living. As I hit my pivot point on the back in to my drive, I broke the side wall bead on one of the wheels. Obviously I was under inflated. From that point on I became much more attentive to tire pressures.
Based on the tire failure poll here on the forum you see an almost 100 % increase in tire failures in the year 3 time period. If the Discount Tire info is correct, it is entirely possible that our ST tires deteriorate enough over their first two years life to be truly unworthy of trusting in that third year of use. Those of use with heavy trailers may need to consider that an ST tire change out might be advisable within year 3 of a tire's life rather than wait for the 5 year cycle that many of us are accustomed to.
Personally it's unacceptable to me to put my ST tires on a 2+ season rotation due to the cost of tires. As many others have done and it makes a lot more sense to move on to the LT tire world, where at least for now, statistics are showing a much better duty cycle.
Here is the link to the entire FAQ.
Trailer Tire Facts - Discount Tire Direct