A car tire pressure check can prevent a number of dangerous situations. If you tire pressure is low, then this can affect your braking distance. In an emergency, this could be very dangerous if you need to make a sudden emergency stop or need to avoid a collision.
Another problem is that over time the low pressure generates heat. For a period this can cause tires to wear out with a moderate heat but if it gets too high then you run the risk of losing tread segments and in the worst case scenario your tires could get blown out completely.