Water and mud in bed

[Northernl]

There appears to be several vents behind the wheel well of my bed on both sides. When it rains an I am driving through water or mud I get mud spraying into the sides of bed. It appears to be mud/water that the rear tires are throwing in the wheel well area. I have a leer top so I should have a dry/clean bed. Why are these vents there and is there a way to close them?

[GregsSD]

Do you have a picture of these vents?
I don't have any kind of vents in mine, and the only water that ever gets into my bed when my Leer shell is on comes from the gap on each side of the tailgate.

[6.0 Bio]

I run a Century topper about half the time, and where I notice water and dirt coming in is through a couple of holes high up on the stake pockets, maybe 5 or 6 inches below the top of the bedrail. Don't know if that's what you're refering to, but if so they would be fairly easy to plug up with a nerf ball or something more permanent. It never really bothered me cause I take mine on and off pretty regular and it gets all dirty in there anyway.