Trailer tire replacement

[bob]

I recently replaced my old titan trailer tires with new goodyear marathons. They were on a 1997 trailer. Had to replace because of excessive cracks in the sidewalls, even though the tread looked like new. I have some questions:
1. What is the general life expectantcy for trailer tires, seems that they never last as long as car tires.
2. My tire dealer said that he recently read in a trade magazine that some tire dressings can actually hurt the rubber in the sidewalls. True?
3. That same dealer said that goodyear only makes trailer tires every 4 or five years so you could be buying a "new" tire that is 4years old and well into a dry rot mode even before it is on the trailer.
4. Trailer boat mag recently had an article on trailer tires where the tire rep said trailer tires should be relpaced every three years. Why? Planned obselesce?
5. I had the tire store check the manufacture date stamped on the sidewall. Guess what? These tires were made in 1998!!!
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[Phil T.]

1. My tire dealer says he has yet to see a tire leak through weather checking. He discouraged the replacement of the Sears/Michelins on my truck until I needed better tread depth (this fall's hunting season).
2. I'm sure there are tire dressings that will shield the rubber from UV, without damaging the rubber.
3. If weather checking is more of a problem than wear, consider covering the tires when the trailer is parked outdoors, like motorhome owners do. They often use pretty covers with brand names on them, but even garbage bags might do the trick.