In areas of extended high ambient temperature, vehicle tires can be affected by a softening of the tire's sidewall. If the vehicle is stationary for long periods, the tire deforms at the point where the standing surface meets the tire.
The tire deformation described is known as a flat spot and is normal tire behavior.
When the vehicle is subsequently driven, a vibration may be experienced from the flat spot. The condition steadily improves with extra mileage.
In order to minimize flat spotting, increase the tire pressures to the maximum, as stated on the tire's sidewall. The tires must be returned to the specified running pressures before driving. See TIRE PRESSURES and TIRE MARKINGS.