The plan was to leave them at the dock. I did a test a few weeks back to see how I could tie them off. You are right, they are very heavy and something you want to leave on the dock.
Many years ago we used tires on our commercial salmon troller. Instead of tying them onto the boat we fastened then to the piling, no floats, via a line through a block which was fastened to the top of the piling, so the tire stayed with the boat as it went up & down with the tide. Yes, they will mark the boat but as we had "rub strakes" so it didn't mark the planking. They do a good job of buffering any impact.