If i have high tire pressure (near limit) and then I load a lot of weight onto the car. Does that mean the chances of my tire being blown out increases? What's the science behind it?

i got around 20 km a liter when i drove a civic 5 spd using advanced hypermiler techniques
and now I drive a salvage nwh20 prius that gets almost to 25 km/l with 195,000 km to date.