Tire pressure is the air pressure inside of a tire, usually measured in pounds per sq. inch. A car tire needs to be at the proper tire pressure. If tire pressure is too high, too little of the tire will be in contact with the road, causing the tire to have less traction and slip more easily. If tire pressure is too low, too much of the tire will in contact with the road, causing increased tire wear and possibly overheating of the tire. Tire pressure is measured with a tire gauge, and should be checked monthly.
Tire design is varied according to the main surface that the tire would be expected to travel on. Any given tire is unlikely to perform equally well on snow, rocky terrain, sand mud and highways.