THE RIGHT TIRE FOR YOUR VEHICLE

There is no universal standard. Most passenger vehicles fall between 30 and 35 psi, roughly 210 to 240 kPa, but the correct figure for your vehicle is on the placard inside your driver's door. It is set by the vehicle manufacturer based on your weight, suspension, and load, and it can differ between front and rear axles.

On the tire information placard inside the driver's side door jamb, and in your owner's manual. Some vehicles put it inside the fuel filler door instead. It typically lists a standard pressure and sometimes a separate higher figure for a fully loaded vehicle. Use the loaded figure when you are carrying passengers and cargo.

Start with the size code, which gives width, aspect ratio, construction, and rim diameter. Then the service description, which gives load index and speed rating. A tire spec chart converts the load index number into an actual weight capacity and the speed letter into a rated speed. Match both against your vehicle placard requirement.

Look at the sidewall of any tire on the vehicle. You will see a code like 245/65R17. That is your size: 245 mm section width, 65 aspect ratio, radial construction, 17-inch rim. Confirm it against the placard on your driver's door jamb, which lists what the manufacturer specified from the factory.

Driving creates friction, friction creates heat, and heat raises the pressure inside the tire. A tire checked right after driving reads higher than its true cold pressure, and setting from that reading leaves you underinflated once it cools. Three hours parked, or before you drive in the morning, gives an accurate cold reading.

Speedometer and odometer readings become inaccurate. Load capacity may be insufficient for your vehicle's weight. Clearance problems can cause rubbing under full steering lock or suspension compression. Stability control and ABS calibration can be affected, and on all-wheel drive vehicles a mismatch in rolling circumference can damage the drivetrain.