How to Read a Tire Size
A plain language explanation of the letters and numbers on a passenger tire sidewall, based on standards published by tire manufacturers and Transport Canada.
Tire sidewall markings are standardized. The example below explains a typical passenger car size such as P225/65R17 94H M+S, using definitions commonly published by tire manufacturers and Transport Canada.
Reading the Example
- P: P Metric classification for passenger vehicles. LT indicates Light Truck, built for heavier loads.
- 225: Section width in millimetres, measured from sidewall to sidewall.
- 65: Aspect ratio. The sidewall height equals 65 percent of the width.
- R: Radial construction, which is standard for modern passenger tires.
- 17: Wheel diameter in inches.
- 94: Load index. Refers to a published load rating table. A value of 94 corresponds to about 670 kilograms per tire.
- H: Speed rating. Refers to a published speed rating table. H corresponds to a maximum of 210 kilometres per hour.
- M+S: Mud and Snow marking. It does not meet the Three Peak Mountain Snowflake standard for severe snow use.
Where to Find Your Correct Size
The recommended tire size, load index, speed rating, and inflation pressure for your specific vehicle are listed on the sticker located on the driver side door jamb, or in the vehicle owner manual. Always verify fitment with a qualified tire professional before changing size or specifications.