or do i need to do anything else to prep the inside of them?

 

Sand them and clean with rubbing alcohol. Then it never hurts to do a couple coats of adhesive promoter before putting on liner. U can get the promoter at ur local parts store in the spray paint section.

 

I sanded mine first time and the paint came off when I hit them with a pressure washer a month later. Today I said fck it and just spray painted them without doing any prep work

 

Oooookay! I have bedlined both of the rear wheel wells using 3M Professional grade bed liner.

For prep, I scrubbed and power sprayed the inside of the wheel wells as best I could, then used a rag and some liquid Sander Deglosser.

Did 2 coats of the bed liner. It came in pretty "black" on the first coat. Doesnt look too bad. Not great, but not bad for my first attempt at something like this.

I find that it's VERY easy to get too close to what I was painting. Make sure you stay back several inches. You'll get a better, more uniform pattern.

Will post more pictures of it tomorrow after it's for sure dry, but here's what one looks like after finishing:




*edit* Sorry for poor quality of the pic. Sun's going down!