A soft tire is a tire that does not have sufficient air pressure to meet the manufacturer's recommended ratings and settings. Each tire manufactured today includes the recommended air pressure ratings embossed into the side wall of the tire. Operating a vehicle with a soft tire can increase the tire's rolling resistance, resulting in excessive fuel consumption. Vehicle handling traits can be adversely effected by soft tires as well. Perhaps the biggest downside to operating a vehicle with soft tires is that the tires wear out at an increased rate when operated at reduced air pressures.
Under-inflated tires are one of the biggest causes of using excess fuel in the world. The American Automobile Agency, or AAA, has stated that operating a vehicle with soft tires can result in a 25-percent reduction in fuel economy. There are many factors which can lead to soft tires. Oxygen is perhaps one of the main factors in soft tires. The molecules that make up the air that is pumped into a tire are small enough that they can seep out of a rubber tire's compound over time.
Temperature and other factors combine to create under-inflation problems. As the air temperature increases, the air molecules grow larger, giving an exaggerated air pressure reading. As the temperature declines, the air molecules deflate, causing the tires to be under-inflated. In an effort to reduce this fluctuation in air pressure, many manufacturers recommend inflating tires with nitrogen in place of compressed air. The nitrogen molecules are not only larger than the air molecules, which prevent the osmosis of the gas through the tire's rubber, they are also lighter than air and create a slightly reduced rolling resistance.
Dangers that are caused by driving with soft tires are tire damage and blow outs. Heat is generated by operating soft tires, and this heat is often linked to sudden and unexpected tire blowouts. An under-inflated tire is also operating with a much wider footprint on the road than a properly inflated tire. In rain or wet conditions, this wider foot print can lead to hydroplaning. Hydroplaning is a condition where the soft tires actually ride on top of the water instead of through the water.
It is a wise idea for people to check the air in a vehicle's tires every month. It is critically important to assess the tire's air pressure after notable changes in the weather or temperature. As fall slips into winter, a tire can lose nearly half of its recommended air pressure. Driving with properly inflated tires helps save fuel and is safer.