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how to tell tire size

You can tell your tire size by reading the code printed on the sidewall of the tire and/or by checking your car’s information labels and manual.

Quick Scoop

Most common tire sizes look like this:
Example: 215/60R16 95H.

  • 215 = tire width in millimeters, sidewall to sidewall.
  • 60 = aspect ratio (sidewall height is 60% of the width).
  • R = radial construction (almost all modern car tires).
  • 16 = wheel (rim) diameter in inches.
  • 95 = load index (how much weight each tire can carry).
  • H = speed rating (maximum safe speed range for that tire).

Where to Find Your Tire Size

1. On the tire itself

Look at the sidewall (outer side of the tire) and find a cluster of numbers and letters like:

225/55R17 97V
P215/65R15 89T
265/70R17 115S

Things to know:

  • It may start with a letter :
    • P = P‑metric, passenger vehicle (common on cars and SUVs).
* **LT** = light truck tire (for trucks/vans needing higher load capacity).
  • There may be other markings, but the width/aspect ratio/R/rim cluster is the main “size” code.

2. On the driver’s door jamb sticker

Open the driver’s door and look at the tire and loading information label in the jamb.

  • This usually lists:
    • Front and rear tire size (sometimes different front vs rear).
* Recommended tire pressure, including the spare in some cases.

This is generally the manufacturer’s recommended size , which you should follow unless a professional confirms an alternative is safe.

3. In the owner’s manual

Your owner’s manual normally has a tire section listing:

  • Original tire size and optional sizes (for some trims).
  • Load and speed recommendations, pressure charts, and sometimes winter tire notes.

Breaking Down the Size Code

Using a typical car tire: 225/50R17 94V.

  1. Tire width – 225
    • First three digits.
    • Width in millimeters , sidewall to sidewall.
  1. Aspect ratio – 50
    • Two digits after the slash.
    • Sidewall height as a percentage of the width, so here sidewall height is 50% of 225 mm.
  1. Construction – R
    • Usually R for radial (internal plies run radially).
    • Other types (like bias-ply) exist but are rare in normal passenger cars.
  1. Wheel diameter – 17
    • Diameter of the wheel (rim) this tire fits, in inches.
 * You must match this number to your wheel size (a 17‑inch tire goes on a 17‑inch rim).
  1. Load index – 94
    • Two or three digits after the rim size.
    • Refers to a chart that translates the number into a maximum load per tire.
 * Example: a load index of 94 is higher capacity than 91.
  1. Speed rating – V
    • Final letter (H, V, W, T, etc.).
    • Indicates the maximum safe speed range the tire is designed to handle under proper conditions.

Quick Ways to Check If a Size Fits

If you already have stock tires and want to confirm a new size:

  1. Match the wheel diameter exactly
    • If your current tire is 205/55R16, the new tire must also be R16 for the same rims.
  1. Keep overall diameter close
    • Too tall or too short a tire can affect speedometer accuracy, handling, and clearance.
 * Online tire size calculators let you compare two sizes and see diameter and speedometer error.
  1. Respect load index and speed rating
    • Do not go below the manufacturer’s recommended load index or speed rating (equal or higher is normally OK).
  1. Follow the door sticker or manual
    • Use the door jamb label and manual as your “home base” and check any alternative size with a professional.

Extra: Metric vs. “Flotation” Sizes

Some light trucks and off‑road tires use another style, like:

  • 31x10.50R15

Here:

  • 31 = overall tire diameter (inches).
  • 10.50 = section width in inches.
  • R15 = radial construction, 15‑inch rim.

You read where it’s printed the same way (on the sidewall), but the meaning of the numbers is slightly different from the metric style.

Mini Example Scenario

You look at your tire and see: 215/60R16 95H.

  • You now know it is 215 mm wide, sidewall height is 60% of 215 mm, radial construction, fits a 16‑inch wheel, with a load index of 95 and a speed rating of H.

If your door sticker shows 215/60R16 95H , then that is the size you should ask for when buying new tires unless a trusted tire shop recommends a verified alternative.

TL;DR:
Look at the tire sidewall for something like 205/55R16 91V , then cross‑check it with the driver’s door jamb label and your owner’s manual to confirm the correct size and ratings.

Information gathered from public forums or data available on the internet and portrayed here.