**Offroaders.com Guide to P-Metric Tire Terminology – P-Metric Tire Sizes Conversion Chart – P-Metric to Inches**

Rim Size | P-Metric Size | Tread Width | Actual Tire Height |

15 Inch | 205/70R15 | 8.7 inches | 26.3 inches |

215/75R15 | 8.45 inches | 27.7 inches | |

235/75R15 | 9.25 inches | 28.9 inches | |

265/70R15 | 10.4 inches | 29.6 inches | |

16 Inch | 225/75R16 | 8.8 inches | 29.3 inches |

235/85R16 | 9.35 inches | 31.7 inches | |

245/75R16 | 9.65 inches | 30.5 inches | |

265/70R16 | 10.5 inches | 30.6 inches | |

265/75R16 | 11.2 inches | 31.6 inches | |

285/75R16 | 12.4 inches | 32.8 inches | |

305/70R16 | 12.2 inches | 32.8 inches | |

315/75R16 | 12.3 inches | 34.6 inches | |

345/75R16 | 13.6 inches | 36.4 inches | |

17 Inch | 235/65R17 | 9.25 inches | 29.0 inches |

245/70R17 | 9.65 inches | 30.5 inches | |

255/75R17 | 10.4 inches | 32.1 inches | |

255/80R17 | 10.0 inches | 33.1 inches | |

265/70R17 | 10.4 inches | 31.6 inches | |

275/70R17 | 11.0 inches | 32.2 inches | |

285/70R17 | 11.2 inches | 32.7 inches | |

285/75R17 | 11.2 inches | 33.8 inches | |

305/65R17 | 9.8 inches | 32.6 inches | |

315/70R17 | 12.4 inches | 34.4 inches | |

18 Inch | 265/60R18 | 8.6 inches | 30.5 inches |

275/65R18 | 11.0 inches | 32.1 inches | |

275/70R18 | 11.0 inches | 33.2 inches | |

285/75R18 | 11.0 inches | 34.8 inches | |

295/65R18 | 9.4 inches | 33.1 inches | |

305/60R18 | 12.2 inches | 32.4 inches | |

305/70R18 | 9.8 inches | 34.8 inches | |

20 Inch | 275/60R20 | 8.9 inches | 33.0 inches |

275/65R20 | 11.0 inches | 34.3 inches | |

285/60R20 | 11.2 inches | 33.0 inches | |

285/65R20 | 11.5 inches | 33.5 inches | |

295/55R20 | 12.4 inches | 33.0 inches | |

295/60R20 | 11.7 inches | 34.5 inches | |

305/55R20 | 12.4 inches | 33.5 inches | |

325/60R20 | 13.0 inches | 35.6 inches |

**The values shown are calculated measurements based on the p-metric formula. Actual advertised tire height and tread width will vary from manufacturer to manufacturer for specific p-metric tire sizes. Check with the manufacturer’s actual dimensions per individual tire brand before purchasing.**

▪ Convert P-Metric Tire to Inches

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▪ Speedometer Converter

▪ Find new Gear Ratio with new Tire Size

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▪ Convert P-Metric Tire to Inches

# Reading a Tire:

All tires are required to have certain information molded into the side of the tire in a location known as the sidewall. Some of the information is self explanatory while other information requires a little knowledge to decipher. The following will help you understand what this information means.

**Tire Type – **This Defines the intended proper use of the tire. P indicates this is a passenger car tire while LT indicates the tire would be for a light truck with a heavier load rating.

**Tire Width – **This is the width of the tire measured in millimeters from sidewall to sidewall. An example might be 215 representing 215 millimeters.

**Aspect Ratio – **This is the the ratio of the height of the tire’s cross-section to its width. An example of this might be 65, which means that the height is equal to 65% of the tire’s width. To calculate the aspect ratio, multiple the first number (e.g. **215**) by the second number with a decimal before the number (e.g. **.65**). Using the example numbers the tires aspect ratio would calculate as **215x.65=139.75 **where 139.75 is the tires height in millimeters. This is the height of the rubber from rim to tread on one side of the tire.

**To convert the aspect ratio to a full tire height in inches, do this:**Convert the above calculated tire height (aspect ratio) in millimeters to inches by multiplying the millimeters by .03937 (139.75 x .03937 = 5.5 inches). Then take the inches and multiply by two and add the rim size. Example: 5.5 x 2 + 15 (rim size in inches) = a 26 inch tall tire.

**Construction – **This indicates how the how the tire was put together and will say much about the tires handling characteristics. **R** indicates the tire is a radial type tire. For more information about what a radial is, click here. **B** indicates the tire is a bias ply type tire. For more information about bias ply type tires, click here.

**Wheel Diameter – **This is the width of the opening in the tire where it would be mounted to a wheel. This is measured from one bead across the opening to the other side of the same bead. This measurement is in inches and an example would be **15** and indicates that this tire is for a 15 inch rim, or wheel.

**Load Index –** This is a number corresponds to the maximum load in pounds that a tire can support when properly inflated. You will also find the maximum load in pounds and in kilograms molded elsewhere on the tire sidewall.

**Speed Rating – **This is a number that corresponds to the maximum service speed for a tire. See Chart for ratings. Note: Speed ratings are specific for passenger car tires and not light truck tires. Light truck tires (LT) are not speed rated.

| Maximum Speed |

Q | 99 mph |

S | 112 mph |

T | 118 mph |

U | 124 mph |

H | 130 mph |

V | 149 mph |

W | 168 mph |

Y | 186 mph |

Z | Above 149 mph |