No play = no travel?

I amy be wrong, but I thought that a team can carry 53 playerws, but only 45 can dress for a game, and that the eight that do not dress cannot travel with the team. IF its a home game they can be on the sidelines (Simms was on the Bucs sideline, but it only affected travel).

As I said, I may be wrong, but I thought I read that once.