Tire age?

This from Carlisle who make ST tires;
Time and the elements weaken a trailer tire.
– 3 to 5 years is the average life expectancy of a trailer tire,regardless of mileage.
– It is estimated that in approximately three years, roughly one-third of a tire's strength is gone
– After three years, depending upon storage and conditions of usage, consider replacing trailer tires even if they have tread depth remaining.
– After five years, trailer tires should be replaced in all cases.

and this from Goodyear who also markets a ST tire;

Tire Replacement Guidelines

Goodyear does not state a specific replacement age for RV tires because there are many conditions that dictate a tire's life span. Some factors that influence how long a tire will last are:

Usage per year - more frequent usage will result in longer life
-Vehicle storage practices (6 months loaded with little or no rotation is not good!)
-Usage in warmer climates can also impact a tire's overall life due to greater extreme ozone exposure .

Good points made above.
I would add if you were making short local trips in your area sometimes we can take a chance on aged tires. But IMO for a long trip where the tires will heat for long periods I would get new ties before the long trip.

6 yrs. May be pushing it. General recommendations are 5-7 years. They will most likely always "look" good, with lots of tread, but its age that is the problem. I would have somebody who knows tires take a look at them, or just replace them. Nothing worse than tire problems on a trip.

Thanks. I do have the bearings and brakes checked annually when I get it inspected. I'll take a close look at the tires when I get her out of storage.

If it were my trailer I would be shopping for new tires. Just sitting without being used is very bad for tires. Look for small cracks in the sidewalls and between the treads. If you see any then get new ones.

There may also be hidden damage inside the tire due to rim rust or other moisture that is inside the tire. Either way, I would shop for new ones and not use those tires.

Also would probably be a good idea to repack the wheel bearings and check/adjust the brakes before you take off.
Barney