I put a rubber floor mat in the box when I bought the truck new in March of 2011 to protect the floor. It has the little rubber knobs in the bottom of the mat.
I read somewhere that these "little knobs" will eventually wear off the paint in your box floor from vibration. I have never looked under it from the day I put it in so I decided I better check it out and there wasn't any paint wear from it. That made me feel at ease.
The only thing I carry in the box is the spare tire which is quite heavy which probably holds it down from vibrating.
I got to thinking maybe I should pull the mat out and turn it upside down with the knobs facing up and the smooth side down so if it does start vibrating it won't wear through the paint.
Then again being flush against the floor might somehow trap moisture under it from the temperature changes and cause it to rust.
Any thoughts on this (turning it upside down).