I looked at Wade's website and no mention on how to clean. You may want to call and ask.
On our coach, we used some carpet that matched our coach interior for the steps and entry. I had the pieces bound and a rubberized bottom attached. We shake ours out all the time, but twice a year I clean them. They collect a LOT of deep dirt and need a good cleaning. I take mine out and lay them on the driveway. I flood them with water, add some carpet soap and scrub, making sure I work on any spots. Once done, I flush them thoroughly, as soap residue is the biggest dirt attractant. I use a piece of plastic, like a wide putty knife, to squeegee the water out. Once done I let them thoroughly dry in the sun all day.
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor