How to Read a Tire Size

Every tire has its size molded into the sidewall, for example 225/45R17. Once you know what each part means, finding the right replacement is simple.

Breaking down 225/45R17

• 225 — section width in millimeters (tread width).
• 45 — aspect ratio: sidewall height as a percentage of width. Lower means a shorter, sportier sidewall.
• R — radial construction (standard on modern tires).
• 17 — rim diameter in inches the tire fits.

Load index & speed rating

After the size you’ll often see something like 94H. The number is the load index (how much weight the tire can carry) and the letter is the speed rating. Always match or exceed your vehicle’s original spec.

Where to find your size

Check the sidewall of your current tire, or the placard inside the driver’s door jamb, or your owner’s manual. When in doubt, search our catalog by size and confirm against your vehicle.