Sounds like you're looking at skates that run narrow and are looking to size up the length to compensate for width. If that's the case it's probably not a great idea. Better if just getting skates that fit you. Obviously depends what you're using them for. For a cruise on the boardwalk I don't think it's the end of the world, but if you plan on playing with them, even lazy pickup, I would avoid. The easiest way to get hurt is gear that fits poorly and skates are the worst