I chucked my Marathons for the Les Schwab tires. Not only are they better, but there's a Les Schwab everywhere, just in case something happens.
Also note - if your tires are more than 6 or 7 years old, replace them regardless of how much tread is left! Treadwear is NOT an indication of a tire's condition on a trailer. The rubber breaks down over time, and weakens. Thus a blowout WILL occur!
Also, as mentioned above, only get trailer tires for your trailer. They are more flexible, which not only "cushions" your boat, but also makes it much safer for towing. Regular car tires can make your trailer bounce all over the place.