How to Locate Proper Tire Pressures for Your Vehicle and Properly Inflate Your Tires

by Contributor

Most people do not know how or when to properly inflate their car or truck's tires because they have not been properly trained and certified (this unfortunately includes some who have posted articles on this subject). This can result in dangerous over- or under-inflation conditions which at best will damage your tires and at worst can cause a deadly accident. Here, I show you how to properly identify and safely inflate your vehicle's tires.

Sample placard. Your vehicle's placard will vary, but it will contain similar information about your vehicle's tires.

Know the Correct Tire Pressure for Your Vehicle! Every vehicle manufactured in the last few decades has been required to be equipped with a vehicle placard. This placard includes not only proper cold tire pressure for front and rear tires as determined by the manufacturer but also OEM tire size, speed rating, load capacity, and other useful information. There are several common places to find this placard on any vehicle: inside the driver's door, inside the fuel door, inside the trunk lid, inside the passenger rear door, inside the glove compartment door, inside the console door, or in the owner's manual. Once you locate this placard, find the correct cold pressures for your vehicle's tires as determined by the manufacturer. This cold pressure may be the same for all 4 tires, or may vary from the front and rear axles. Take good note of these OEM pressures. They are the only correct cold pressures for your vehicle's tires (unless you have significantly changed your tire size from the OEM specification).

Check Tire Pressures when the Tires are COLD! Tire pressure is affected by temperature. Identically inflated tires will show different pressures if one has been driven and one has not. The "hot" tire that has been driven will show higher pressure than the "cold" tire that has not been driven. It is important to understand this difference between hot and cold pressure. Tire pressures should be checked when your vehicle's tires are "cold." Cold pressure is the pressure in the tire after it has been sitting for several hours and not driven. Mornings are a good time to check tire pressures, after the vehicle has been sitting overnight. If cold tire pressure is HIGHER than the cold pressure specified by the manufacturer, let air out of the tire slowly, checking the pressure every second or so, until it is at the manufacturer's specified cold pressure. Now this tire will be at the correct "hot" pressure when driving.

If cold tire pressure is LOWER than the manufacturer's specified pressure, drivers should note the difference between this pressure and the specified pressure then drive to the nearest tire fill location (perhaps a convenience store), and check the pressure again now that the tire is warm. To this warm pressure, motorists should add the difference in actual measured cold pressure vs. specified cold pressure noted when the tire was cold. For example, a vehicle has a specified cold tire pressure of 30 psi. One tire, however, gauges at 26 psi cold, or 4 psi lower than the specified cold pressure. So we note that there is a difference of 4 psi for this cold tire. This 4 psi difference will need to be added to the tire. To add this 4 psi, we would drive to the nearest tire fill location. But now our tire is "warm" and now gauges at 30 psi, an increase of 4 psi. Although this hot gauge is the same as the specified cold pressure, the we must still add 4 psi to this "hot" tire for the correct tire pressure. When this 4 psi is added, the hot tire will now gauge 34 psi, the correct "hot" pressure for the tire. Remember: when this same tire cools back down after several hours of not being driven, the cold tire pressure will now gauge correct, or 30 psi.

NEVER INFLATE TO MAXIMUM TIRE PRESSURE! There is a common misunderstanding that a tire's pressure is stamped on the sidewall. In actuality, this pressure stamped on a tire's sidewall is the MAXIMUM COLD PRESSURE that the tire will safely hold. Many tires are rated for a maximum cold pressure of 44 psi, to allow the tires to be used on a wide variety of vehicles. Some vehicles may only require 30 psi cold pressure, others may require 38 psi cold pressure. In both cases, this cold pressure is less than the tire's MAXIMUM cold pressure, so the tire can safely be installed on these vehicles. Tires should be inflated according to the manufacturer's cold specifications as described in steps 1 thru 3 above, not the maximum pressure stamped on the sidewall of the tire.

Tips

  • check Over-inflated tires, even those inflated to maximum pressure, will cause problems with ride comfort, stability and handling, uneven wear, and potential tire failure.
  • check Under-inflated tires will also cause these same problems, but under-inflated tires have greater potential for tire failure.
  • check When in doubt about your tires, stop by your local reputable tire dealer and inquire at the desk. They will be happy to check your tires and tire pressure.

Warnings

  • close NEVER inflate a tire beyond its maximum rating!
  • close NEVER drive a tire that is severely over- or under-inflated, or it may fail and blow out!
  • close ALWAYS have your tires installed by a trained and certified tire professional.

Items you will need

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.