Just gonna say the policy is there in black and white:
A firearm may only be used when there is clear and present danger to life and other non-lethal methods are inappropriate or have failed.
Firearms should never be used to apprehend a fleeing suspect, unless justified in the point above.
There's no justification for shooting a parked cars tires when you have roadspikes to make sure it's not used to flee. There's also no reason to shoot at a vehicle unless the drivers actively attempting to kill someone or has been with no intent to flee.