NASCAR Racing: Credentials, nascar trailer, drivers teams

Question
Is there a place where you can see what type of credentials will get you into what areas? There seem to be many different types but no one place that explains what they are good for. So far my method is to keep going until someone stops me.

Answer
Credentials are only available to the drivers, teams, and media. I think you are talking about pit/garage passes. They can get you into the infield at the tracks. Garage passes can get you in the garage before or after practice, not during practice. Credentials are not for fans you have to go to the nascar trailer to get credentials. Credentials get the media unlimited access to the garage, they also allow the drivers and crews to come and go as they please