My truck came with OEM moulded mudflaps. Personally ai didn't like the look at took them off the day after I got the truck. They made the wheel arch look massive, which made the 20" wheels look tiny. I chose to have Xpel installed down both sides of the truck to protect against rock chips.
I recently installed larger Duratrac tires. I have noticed they pick up much larger stones from the construction sites I'm on verses the stock highway tires. I have orderd some gatorback mudflaps. They are a flexible rubber. I'm hoping they areally going to look better, and shed snow build-up easier than the OEM ones.
If you are going to do mudflaps, so all 4 corners. It will help crud from shooting up and rusting out behind the tail lights.