Driving around on under inflated tires isn't a good idea at all because Under inflated tires can increase your car’s rolling resistance, which it leads to a drop in fuel efficiency since it takes more energy to move the vehicle down the road.
If one single tire is down by ten pounds of air means a 3.3 percent drop in fuel economy, can you imagine if you multiply that by all four tires? You can figure on giving up ten percent of your gas mileage. The added friction and rolling resistance also means more heat is generated, and heat is the enemy of the internal structure of a tire.
That heat we are talking about will definitely damage a tire to the point of failure. "Studies show that under inflated tires are a full 25 percent more likely to fail, and at least half of one-car accidents involve a tire problem as a factor. And still, it’s estimated that 60 to 80 percent of the vehicles on the road are rolling on tires that are low on air."