hawkeye-08 wrote:
We bought an used 1998 Terry trailer in 2008. It had the original tires, previous owner keep the trailer inside shop for storage, under car port during the season. We had to replace the rubber valve stems due to leaking, but the tires lasted until 2013. I'm not saying all tires will last that long, but they can. Check the pressure each time before you go out, make sure you have a good spare.
Keeping tires on a trailer that long is just plain dangerous. Granted, keeping the trailer stored inside and avoiding UV exposure can extend tire life, but it is much safer to change tires much sooner than that. I keep our trailer stored inside, but I wouldn't think of keeping one set of tires on it for for close to 15 years.