Tire pressure is the net pressure of air in the vehicle's tires, expressed in pounds per square inch. It is necessary to check the tires' pressure with a pressure gauge as frequently as possible.
When inflation pressure is too high, then tire touches the ground marginally making the vehicle bounce around on the road. This makes traction suffer and increasing the stopping distances. The ride comfort may also be compromised.
If inflation pressure is too low, the tire's surface area that touches the ground is too vast, which increases friction. The tires will wear prematurely due to this apart from getting overheated.