I'm installing a new toilet on newly installed porcelain tile. I tested the way it sits on the tile without the wax ring, just setting in place on the foor where it's supposed to rest. The rim of the toilet base did not touch the tile; it was held up off the floor by something in the center of the base. I turned it upside down and saw that there are ribs molded into the bottom of the toilet to help support it. However, theses ribs protrude lower than the rim of the base, and prevent it from touching the floor. Can I, should I, grind or file down these ribs so they are even with the rim of the base?
[The old flange was replaced when the tile was installed. It's screwed into the backer board and is slightly higher than the top of the new tile.]