For no apparent reason a C210 ran off the side of the runway on the landing roll in a modest cross wind.

Narrative

Immediately after landing on Runway XX; the plane veered toward the left side of the runway. I tried to keep it on the runway with the rudder pedals; but the plane felt like it might tip over onto a wing (I don't currently recall which one) and the back of the plane started feeling a little light; so I tried to compromise between straightening it out and letting it veer off the side of the runway into the grass. I do not recall my aileron input during the attempted recovery. The plane rolled into the grass and came to a stop. Per information Papa; the wind was 270 degrees at 10 KTS. I do not remember anything special about the landing until the plane started veering toward the left side of the runway. After thinking about it; the possibility that seems most likely to me is that I didn't fully get out of the crab; so when I touched down the airplane headed for the left side of the runway. Or maybe I relaxed after touching down; and the wind caught the tail and/or a wing. In either case; I don't really know why I did it. I have over 800 hours in that specific plane; and believe that I have landed in more challenging conditions (e.g.; stiffer crosswind on narrower runway) before.