This three-digit number gives the width in millimeters of the tire from sidewall edge to sidewall edge. In general, the larger the number, the wider the tire. Source: safercar.gov
This two-digit number, known as the aspect ratio, gives the tires ratio of height to width. Numbers of 70 or lower indicate a short sidewall for improved steering response and better overall handling on dry pavement. Source:safercar.gov
This is the Rim Diameter code. This two-digit number is the wheel or rim diameter in inches. If you change your wheel size, you will have to purchase new tires to match the new wheel diameter. Source:safercar.gov
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Where do I find my tire size?
To find your original equipment tire size, load carrying capacity, speed rating and PSI (cold) inflation specifications, check your vehicles’ placard.
Where is the placard located?
If you have a newer vehicle, the placard is located in the driver’s side doorjamb. If you have an older vehicle, look for the placard in the rear doorjamb, glove box, under the hood, in the fuel door or in your owner’s manual.
How do I read my tire size on the placard?
The following diagram illustrates some of the important aspects of your tire size:
Metric Type (P)
Aspect Ratio (65)
Construction Type (R)
Rim Size (15)