Tire maintenance is very critical on a vehicle weather its a car or lite truck. Atleast once a month the air pressure should be checked on tires, and inflated back to 35Psi on most vehicles. Some heavy duty trucks require more. It is recommended to look at the owners manual for  propper inflation.

Never over inflate or under inflate a tire because that will cause a safety hazard, and can cause the tire to explode, or blow out during driving. Tires should be rotated every 6,000 miles, and balanced to get the maximum milage out of them. The wheels should be aligned every 12,000 miles to help tires wear evenly. The maximum safe wear limit on a tire is 3/32.  There are speacial tools to check the tire wear, sold at auto parts stores for only a few dollars.