Maybe 6 months even though I skate 54-56mm wheels, I do a lot of lipslides. Sometimes, my wheels get flatspotted, but even weirder is when they get oblong. They wear out unevenly to where they are no longer round. Since I'm older, if I flatspot wheels, I'll give them up as a lost cause. I don't have time to waste hoping they'll even out. Shit, I'll give a kid an old set of wheels from my car if their wheels are so flatspotted that they're distracting me.