Tires: replacing a single tire on a 06 awd cadillac sts4, awd system, tire diameter

Question
I hit a pothole the other day which caused a belt to snap in my front passenger tire. So after calling around to get a replacement i was told that if i were to replace one tire
That i would also have to replace the other 3 . To prevent possible damage to the drive train. Ive done a bit of research and have heard 2 different answers
1. Is yes i will have to buy all 4 and 2. No it doesn't matter due to the open center diffiruntial.  Please shed some light

Answer
Juan,

You need to ask Cadillac this question.  It's their car and they know how their AWD system works.

Some AWD systems are really sensitive to differences in tire diameter - Subaru comes to mind.

But some aren't - and there are so many different kinds, it's impossible to keep track.  That's why the rule of thumb is to replace all 4 on AWD and 4X4's.  That's a safe, always correct answer - one that tire shops can fall back on with confidence that they will be doing no damage to the vehicle.  One that won't get them sued.

But it isn't the least expensive answer.

So without information from Cadillac that it is OK, then you need to fall back on replacing all 4 - unless you are willing to accept the risk.