Seems like the consensus on both RVNet and Hybrid Explorer has been that at the 4 - 5 year mark BASED ON THE MANUFACTURING DATE, NOT THE APPEARANCE - that the tires need to be changed. We take at least one trip to FL each spring and then one longer trip in the summer, so we generally go with the 4 year time for peace of mind. Doesn't matter it they're the less or more expensive or what they look like, trailer tires aren't the same as auto tires and need to be changed.
If you haven't searched for the manufacture date on your tires, they'll be a 4 digit number right alongside the rim. Something like 2412 would mean they were manufactured the 24th week on 2012. Sometimes the darned code is on the inside and you have to crawl around with a flashlight, but you need to know. When time comes to replace the current set, tell the supplier up front that you will not accept tires with longer than a 6 month old manufacture date. You could be buying tires that have been sitting on a shelf for 2 or 3 years, which would mean you'd be ready the next year or so to replace them even though they were never on the ground.
Trailerless but still have the spirit
2013 Rockwood Ultra Lite 2604 - new family
2007 Rockwood ROO HTT - new family
2003 Ford F-150
4 doggies - We support Adopt/Rescue.
Sam, you were the best!
Cubbie, Foxy, Biscuit and Lily - all rescues!