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Find your wheel size

Find the inch size already printed on the tire sidewall and on the driver's door label.

Here's what you need

  • The tire that's on the car
  • The driver's side door
  • The owner's manual, if you have it

Read the printed size

  1. Open the driver's door.
  2. Find the Tire and Loading Information Label on the driver's side door edge, doorjamb, or post. NHTSA says that label, or the owner's manual, shows the correct tire size for the vehicle.
  3. Read the size code on the tire sidewall.
  4. Use the two-digit number after the letter R. NHTSA calls this the rim diameter code, and it is the wheel or rim diameter in inches. In a code such as 225/45R18, that number is 18.
  5. If the size is not printed and you need to measure, open how to measure a wheel for a protector.

Things you should know

  • NHTSA says the greatest air pressure marked on the tire is not the pressure the vehicle maker recommends. Use the door label or the owner's manual for that pressure.
  • NHTSA says a "P" at the start of the size means a passenger-vehicle tire. "LT" means a light-truck tire. "R" means radial.
  • The three-digit number is the nominal width in millimeters. The two-digit number before R is the aspect ratio, the tire's height compared with its width. Those are not the wheel diameter.
  • The last four digits of the DOT tire identification number are the week and year the tire was built. They are not the wheel size.
  • On a newer vehicle, NHTSA says the label is on the driver's side doorjamb, called a B-pillar. If there is no B-pillar, look on the rear edge of the driver's door. If that edge is too narrow, the label may be on an inward-facing surface next to the driver's seating position.
  • A listing that uses the word universal does not name one diameter. Read what a universal listing means.

Sources