Cupped Tires

• Some tires eventually start to look as if slight dips are worn into the normally smooth tire surface. This is called "cupping" and happens if the vehicle suspension system is not working properly. This causes the vehicle to bounce, which leads to excessive wear on the parts of the tire that hit the ground as the vehicle bounces. The dips in the surface cause the tires to run unevenly on the road, generating a loud noise.
  
  

Tread Design

• The tread pattern on a set of tires can increase the amount of noise they produce. Tread designs that are knobby and jagged, such as those popular on off-road vehicles, often are louder than their smoother counterparts. Some manufacturers make effective off-road tires that are not exceptionally noisy, but a rougher tread can cause increased road noise if it has not been designed to minimize the sound.
  
  

Improper Inflation

• Like a cupped tire, improperly inflated tires press against the road in an uneven pattern. This can cause increased tire noise, and at a different pitch that might be much more noticeable. Driving on under-inflated or over-inflated tires for an extended time will cause the tread to wear unevenly. This leads to a condition similar to cupped tires, and will cause more road noise even after the tires are properly inflated.
  
  

Failure to Rotate

• If the vehicle's tires are not rotated regularly, the result can be additional road noise from the tires. Tires are rotated to ensure that all four tires wear evenly. Most manufacturers recommend tire rotation every 5,000 to 10,000 miles. If you neglect to rotate tires, they eventually will wear unevenly and cause the noise to increase.