.44mag is needed to punch through a radiator, but go ahead and go ask /k/, or any professional, if shooting tires will stop a car.
When you shoot tires, the biggest hole you make is approximately half an inch, and won't puncture the rim. It will cause a slow leak, and the car will still drive for about 40mi before the tire is actually flat. In order to stop an approaching vehicle, you have two options.>1. Put as much lead into the engine block as possible to stop the motion of the engine and stop the car.
This still causes the car to slow rather slowly, and might still travel 100yds depending on speed.>2. Shoot the driver
This will cause the driver to be incapacitated, which will do numerous things. The threat is now dead, and the car is under control from a rag doll (assuming you managed a head/heart shot). The car may veer off to a side, or accelerate rapidly, or brake, or all/none of the above, depending on the action of the perpetrators body.
Remember anon, shooting through glass from the outside, your bullets deflect down. From inside to out, they go up. Make a mental note of that.