F 150 2WD Pickup V8-4.6L CNG SOHC VIN 9 (1997)
If the road test indicates there is tire whine, but no shake or vibration, the noise originates from the contact between the tire and the road surface.
A thumping noise usually means the tire has flat or soft spots making a noise as they slap the roadway. Tire whine can be distinguished from axle
noise because axle noise diminishes or changes according to load or speed. Tire noise remains the same over a range of speeds.
To verify that tire noise is not associated with shake or vibration, inflate the tires one at a time to 345 kPa (50 psi) and check for a change in the
sound. The pitch or whine will change as the increased pressure changes the tire frequency.
CAUTION: Be sure to deflate tires to their proper pressures after this check is completed.
