The contents of those apartments contain wheels, gears are wheels, so anything that requires gears has wheels, so a proper clock is filled with wheels, then you have rollers, any sliding door will have rollers, thus having wheels, immpretty sure some of those slow self closing door mechanisms have cogs in them, so more wheels. Your fridge has 2 wheels to make the motor work, so more wheels, nearly every single slide out drawer has wheels to help the draw slide out, so say 4 wheels each drawer and you have like 5 drawers, that's 20 wheels, your vacume cleaner has wheels, some beds have wheels, wheels will always out number doors.