I have been fighting trailer lights going out for the past year plus, West Marine replaced them numerous times for me under warranty but I was getting tired of it. To make a long story short I just finished up this evening installing LED lights all around.  I found my main shorting issue in the "over 80 inch" tail lights. I was surprized at how sloppy a wiring job had been done with the inline taps as who ever did the job had had left an exposed tail at every inline tap connector.
  All my trailer lights now work and are bright and did a little driving test up and down my rough pot hole filled alley.

  The following Trailer wiring diagram was really helpfull: http://www.bbcboards.net/zerothread?id=195398

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.

I got the Goodyear Marathons on line last year As the ones on there were very old & the side walls were starting to crack. After reading a lot of post I felt the Goodyear brand were the best. One thing to look for is when you buy the tires check how old they are you don't want something that has been sitting on a shelf for 3yrs.

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.

Just posting to remind everyone to give your boat and trailer an early season check.  With a a lot of trailering miles to come, you don't want any issues to come up.  Recently I have been noticing what looked to be a wobbly tire when I looked in the side view mirror.  I thought my eyes were playing tricks on me, maybe the tire had mud on it and it just looked weird ?  I finally trusted my instincts and jacked up both sides to inspect.  I found the tire was not spinning true when looking at the inner tread depth area and both tires had a high spot.  This is likely due to cord seperation inside the tires and this is how blowouts come about.  I have always ran the recommended pressures, and with both tires doing the same thing I must of got a bad batch.  The tires are GoodYear Marathons, and although you hear a lot of bad things about them on the forums, I am going to run them again.  The tread on them were half gone compared to my new spare, so they had some miles on them for sure.  
Just wanted to give a heads up, don't run the tires under-inflated, and see if they are spinning true when you are driving slowly.  I have a feeling the tires were like this during our trip to the Silver Lake Open, so it could of been a lot worse.