Who knows how they function?

Bullet proof tires are sometimes refered to as a "no flat tire" Simply the inner walls of these tires are coated with another layer of a gummy rubber substance that swells and reacts with the air. So as soon as there is a punture either by a bullet/nail etc. the inner compound swells to reseal the hole.

Also the inner wall or sidewall of these tires are much stronger that ordinary tires. The are designed to carry the weight of the vehicle some distance.

I dont want you to be confused that "bullet proof" tires means that bullet cannot penetrate. No such thing. it will only allow the car to drive for a while for you to get out of danger zone. The approoriate term for the tire is "bullet resistant".

There is a split second window between dying and living. These tires are on designed to buy you that precious seconds. A punctured tire will go about 250km driving at about 100km/hr before it shreds apart. if you think about it, thats a long way away from the enemy. i hope this helps