I'm with Dutch. 36v is always better if you can swing it. TMs are on that list of things you can't have too much of.
That said, I ran a big 24 on my 18' Ranger and did fine. Fished a lot of wind, and the upper Mississippi, with it.
I've gone to Goodyear Endurance for my tires, and they've been excellent so far. Not sure if they're available in 14". Improved the way the trailer pulls.over my old Marathons, and it's actually more comfortable on a 4hr pull.