How can I protect a hardwood floor from a rolling office chair?
In two old homes now I've shredded the wood floor under my chair, monster splinters eventually emerging.  I work at home in semi-rural New Hampshire.  I think they're very old pine floors, so softwood.  I plan to try Shepherd Brand Urethane Casters after putty and repainting.  



From the manufacturer's site, "Nylon tread for carpeting, and urethane tread for hard floors."  Much buzz on Amazon about these. 

Edit: After months with the new casters there are no new paint flakes or splinters. I haven't repainted the floor yet, but it appears these casters will do the trick.