If this is in the wrong place, please delete. I'm in the market for new tires for my tandem axle boat trailer, ST175/80/13, load range C. The trailer originally came with the Goodyear Marathons which lasted a long time. I replaced with LoadStar Karrier radials when the Goodyear's became dry-rotted. The LoadStars have been an incredible tire but are now 7 years old and showing cracking on the sidewalls. My boat is a 23' aluminum fishing boat which weighs around 3200 pounds fully loaded with gas and all gear. I tow it roughly 300 miles in the spring to upstate NY, 300 miles back home in the fall, and about 200 miles during the season, as the boat launch is approximately 7 miles from the house. So, under 1000 miles a year. I went with the Karrier radials for their heat dispersion abilities and the smoother ride. I've noticed the sidewalls are soft, which does allow the trailer to sway slightly, but they've lasted and I have no complaints. I've read that bias-ply tires have a stiffer sidewall and help with the sway, but they aren't great on long trips and don't handle the heat like the radials do. I'm not sure if my 300 miles constitutes as a long trip, but what's everyone's feelings between radial and bias-ply for my situation? The trailer is rated at 5800lbs. The marine superstore I get all my equipment at has the LoadStars in both radial and bias-ply, as well as TowMax radials and bias-ply. Thanks for the help!