get a metal lathe and a chissle and grind off the flant spot.
my sister allways puts flats on her wheeles so i grind them off.
you need to bolt the wheel other wise it will move
i was hella pissed i got sliders and was doin a gap over pebbles and i got caught up on one and slid for like 10 feet and it hasnt worn down this was a few months ago
My flatspots usually ride out in like a day or two. If they don't I take them to school and wack them on the belt sander in metalwork. Then go and wack up another pair of homemade bars. lol.