As you know, tires is only the part on the car that actually touchs the road.
Tires should be inspected regular from wear, nails/rocks, and of course air pressure is the most important of all. Correct tire air pressure not only save gas, it also produce ride comfort. Tire treads also provide grip (traction) and better stopping.
Wheel alignment is also needed requirement to gain tire life, such as Toe, Camber will effect the wear of your tires, so each two or four tire replacement you should always do a front-end or 4-wheel alignment, including inspect of your suspension for freeplay and wear.