Understanding Tire Pressure and Load Limits
Tire inflation pressure is the level of air in the tire that provides it with load-carrying capacity and affects the overall performance of the vehicle. The tire inflation pressure is a number that indicates the amount of air pressure– measured in pounds per square inch (psi)–a tire requires to be properly inflated. (You will also find this number on the vehicle information placard expressed in kilopascals (kPa), which is the metric measure used internationally.)
Manufacturers of passenger vehicles and light trucks determine this number based on he vehicle’s design load limit, that is, the greatest amount of weight a vehicle can safely carry and the vehicle’s tire size.The proper tire pressure for your vehicle is referred to as the “recommended cold inflation pressure.”
Remember, the correct pressure for your tire is what the vehicle manufacturer has listed on the placard, NOT what is listed on the tire itself.
Because tires are designed to be used on more than one type of vehicle, tire manufacturers list the “maximum permissible inflation pressure” on the tire sidewall. This number is the greatest amount of air pressure that should ever be put in the tire under normal driving conditions.