Thanks to herk7769
for an excellent explanation of why being level is important. From other posts I've gathered that it's important, but the mechanics of "why" exactly had escaped me. But I definitely get it now.
Originally Posted by RickV
In post #5 you stated "The dealer used the "two fists" measuring method to check bed-to-trailer clearance". I was just asking where does that come from? I am trying to figure out what the clearance should be or should I just be concerned that front and rear is level? I have never measured rail to trailer or front to rear I have eyeballed front to rear and it seems dead on.
The truck-to-trailer clearance largely comes into play when maneuvering at low speeds on sharp inclines/declines where the truck's tires meet the grade before the trailer does -- thus the two pivot and could come into contact. Another poster gave the example of a railroad track crossing that was 3 feet higher than the road with short ramps up and down.
Based on other forum posts, if you have at least 6" you'll be OK in just about all situations. If you haven't hit your truck with your trailer, you probably have at least that much clearance. This issue came into play for me during the installation of my hitch. When they first had it installed, the clearance was about 3 inches. They fixed that by raising the hitch height. But then the point of this post is that by raising the hitch height to make enough clearance, it was no longer level front-to-back.
I have a hitch with 4 airbags so I also have side-to-side motion that needs proper bed clearance.