What percentage of American children live in poverty? According to the National Center for Children in Poverty, 16 percent of children (20 percent of children under age six) in America live in poverty. The child poverty rate in America is often two to three times higher than that of other major industrial nations. Poverty is defined as living in families with incomes below the federal poverty line ($21,200 for a family of four in 2008).
The main cause for tire cupping is worn suspension allowing too much freedom for the wheel to bounce and vibrate, specifically shocks/struts and bushings. If your wheels are going out of balance, this issue is greatly amplified.
A major factor that usually causes tire noise is the air chamber inside the tire. The large void that is filled with air acts as a giant resonance chamber. Thus, the tires are something like donut-shaped drums that generate a low-frequency hum when tires are rolling.