Thinking of buying a Harley are you?
If the trailer has a wood floor, it's a good idea to nail down 2X4's to help keep the wheels in place, or bolt down some large angle iron, especially of it is a metal floor. At any rate, tie down the bike high and low on the frame at both ends. Tying down at 4 points at both ends (2 on a side) will stop the bike from tipping and keep the wheels from slipping out from under it.
