I have a Sea Ray 240 Sundeck being pulled by a Chevy Suburban 1500 4WD. When towing I get a lot of shake. I cannot tell if it is coming from the trailer or the truck but I’ve never had any shake issues towing other trailers to it make me think it’s the boat trailer. Also the shake is there at almost any speed but it's worse at certain speeds. Where would you start to troubleshoot this problem? Should I get the trailer tires balanced?
I believe in balancing my trailer tires. If you have some try changing tires AND rims, could have on a rim slightly bent. To separate the 2 issues try towing another trailer with your truck and look for shake.
Balance tires and check bearing clearance too. Rim should be inspected too but if the technician is good he will tell you righ away if the rim is an issue.
What you are describing sounds like a ply separation. Jack up each wheel on the trailer and spin it. I'll bet that you will see one of your tires has a tread that is not straight.