I was just going to remove my 98 xj sport flares and sand them, then paint with one of the textured bed liner paints, then someone said it doesn't work good on plastic and when sumer comes it will expand and crack and such.

Sounds kinda iffy to me, whats up?

 

Any time you're doing plastic, make sure you put some adhesion promoter on there first. It'll help the bed liner stick to the plastic a heck of a lot better. As for expanding/cracking, never heard of it myself and I've been dabbling in paint and body work for 20 years. On the plus side bed liner is cheap, and if you're going with a solid black color it's easy to fix and respray.

 

Guys bedline their whole Jeeps. So I don't see why not.
What you are saying I don't think I have read before.
Thinking like with most things prep is key.
And like Camarobli13 said touch up is easy.
I went a different route. Line-X. Not cheap but pretty cool and seems to be holding up.
Not flares but other pieces like door molding, roof skid strips, rear mud flaps, and a couple other things.