You're in a hurry. To the mall, to an appointment, to visit relatives or friends; you're running late. So the great question raises its head: Shall I use the bathroom before the trip or after I get there?
I used to think that this was an interesting question, open to debate regarding such issues as bathroom quality, politeness in using the facilities elsewhere, etc. But today I got the ironclad answer to this question, at least for all trips involving a car: Use the bathroom BEFORE you get the flat tire.