The mirrors on your doors should fold in very easily. I’m not referring to the part you adjust; I’m referring to the mirror base. Disaster Dan posted about this a while back, but I figured I’d post some pictures to help explain. As Dan found out if the mirrors don’t give, something’s going to break.
Re-greasing your mirrors every now and then will help ensure you aren’t buying a new mirror, because that tree got a little to close.
On the bottom of the mirror, there is a big nut. Once you remove this nut, one washer, one spring base, and one spring should fall out the bottom, then the mirror should pull out the top, right out of the mount. Odds are if you’ve never greased yours, be prepared to fight it a little.
Clean off any rust and corrosion that is on everything, then grease everything, in particular the spring base and the little teeth on the mirror stud where they rotate.
When putting these back on, don’t over tighten them, the threads should basically be flush with the nut, the mirror should still fold forward and back fairly easily.
This is a pretty simple task, and will help ensure your mirrors stay in one piece.