I am planning to repaint the roof and window pillars of my truck for the same reason.
The paint was done back in 1999 or 2000 in DuPont Chroma. Most has held up well.
These fender flares are made out of urethane. I don't know if a flex agent was used then.
The paint I plan to use is the PPG "Shop Line" brand (base and clear).
Do I need to add a "flex agent" to the paint just for the flares? Shop Line has Flex Additive "JX993" available. If I need to use it, do I put it in the base and clear coat?
Also, if I need to use that, would I (can I) just mix up a quart and spray the same mix on the roof (which is metal) so I don't need to mix a different batch for the roof and for the fender flares?
Ford Pic 2017 by [url=https://www.flickr.com/photos/152383962@N02/]