I agree with Darryl G but want to add. A Zero turn when the engine is running does not use brakes to stop. It uses the wheel motors. When you stop and turn off the mower the hydros kind of hold your mower in position but the brake is what stops the mower from moving. So if when it is on the trailer your brakes keep the mower in place. If it is moving you need to adjust your brake for the right side. You have EZT hydro's and they have a cam for the brakes. If the right tire is moving then it is way out of adjustment or broken. Look in from under the engine in the back. You should be able to see the brake on each side. One will not be contacting the brake. Tighten or loosen the nut till it touches the cam.
While transporting my zero turn to and from my job sites! The lawn mower rear right wheel tend to move. However it stops very well while in use. Any suggestions on what need to be fixed or adjusted.:frown: