Good reminder Chris!  Trailer tires need to be replaced every 5-7 years, regardless of how they look or how much tread is left on them.  The materials deteriorate over time - faster if your trailer is stored outside.  That's why you hear of blowouts happening to "perfectly good tires".....ones that are typically older than 6 or 7 years old.

It's also a good time to go through your boat with a screwdriver and tighten every screw you can find.  If you've never done this before, you might be surprised at how many work themselves loose.  I check them every year.  Especially check the trolling motor mounts, or one day you'll spear a wave with disastrous results - and an expensive fiberglass repair bill.

In addition, check the mounting bolts on your engine.  They sometimes have a tendency to slowly back out over time.  I check mine every spring, and a few of them usually need a turn or two to tighten them back up.

I got mine from the GoodYear warehouse in seattle so I bet they are fresh.  They have redesigned the sidewall, at least the graffics since 5 yrs ago thats for sure.  I'm sure I'll get another 5 yrs out of them which is all that can be expected.
My spare is already new because of the Silver lake launch ramp a few yrs ago.