The rockers are aluminum (unlike the rear which is ureathane) and that edge's paint in particular takes a beating from rocks and road debris. On track cars they turn almost white as the paint gets sand blasted off from slicks. The only cure is to paint, then clear bra, but over time the clear bra can get pinholes. I have a red viper and I use a 3-M tape that is made to mask stucco applications. Stronger then painters tape but it can be removed and won't damage your paint.
Here's a picture of my viper, when I track the car I also put the tape on the rocker panel top to bottom near the front. Not a perfect red match but inside the fender behind the wheel you can really tell and it sure saves the paint there. On the track clear bra helps but the rockers really take a beating and I have nicks and holes on the clear bra , that's why I tape the sides. good luck, Mike