Trailor Tires

 Hey Ed call dockside marine.  They have a bunch listed on craigslist. just bought a couple ONE HECK OF A DEAL   here is the number (724) 775-4289

What Chauncy said (at least from the reviews I have read).
 
These get good reviews. http://www.etrailer.com/Tires-and-Wheels/Kenda/AM30820.html
 
I think Walmart sells Loadstar/Kenda and they are made in the USA (at least some of them).
 
How big is your boat/weight and what speed rating do you want?  ST's are rated 65 mph max., I think.

http://www.walmart.com/ip/Hi-Run-Boat-Trailer-5.30-12-6-Ply-Boat-Trailer-Tire/23597312?action=product_interest&action_type=title&placement_id=irs_middle&strategy=PWVAV&visitor_id=69992417457&category=0%3A91083%3A1077064%3A541326&client_guid=d9442189-e820-4fe6-bb1d-1ac0434c6d1a&config_id=0&parent_item_id=23597327&guid=e8cd8ffe-f26a-47cb-bd85-62664717a20f&bucket_id=irsbucketdefault&findingMethod=p13n

Kudos Eman, more folks should pay closer attention to their trailer tires. I replace mine every 3 years. Trailer tires aren't designed for the life of a car/truck tire and mileage kills them, not as often as the sun or being overloaded. I'd recommend getting the highest weight rating you can find in your size...

I bought some sports track tires and they came from a tire store.  It was the only brand that they carried.   Less than 200 miles  and the cords were showing through right down the center of the tire.  Had to fight with 2 managers to get them to replace them.  No matter what tires I buy they only last a year and I replace them.  Fishing and hunting close to 200 days a year tires don't last long.