Tire Diameter Unit Converter
Switch tire height between mm and inches. Use the calculator below. Results update as you type.
Overall Diameter = (Rim Diameter × 25.4) + 2 × (Width × Aspect Ratio / 100)How the Tire Diameter Unit Converter Works
This converter works by multiplying an inch diameter by 25.4 to get millimeters, or dividing millimeters by 25.4 to get inches. It handles tire heights from small car tires to 40 in off-road tires.
- Enter a diameter in inches, for example 33.
- Read the result in millimeters: 838.2 mm.
- Read the result in centimeters (83.8 cm) and feet (2.750 ft).
- Enter a size code instead to get its computed diameter in every unit.
The Formula
The formula is Diameter (mm) = Diameter (in) × 25.4. It accepts a size code too, using the standard diameter formula first.
Diameter (mm) = Diameter (in) × 25.4 Diameter (cm) = Diameter (in) × 2.54 Diameter (ft) = Diameter (in) ÷ 12 Overall Diameter = (Rim Diameter × 25.4) + 2 × (Width × Aspect Ratio ÷ 100)Worked example: a 37 in tire is 939.8 mm, 93.98 cm and 3.083 ft tall.
Conversion Table
The conversion table converts 14 tire heights from 22 in to 40 in into millimeters, centimeters and feet. A 22 in tire is 558.8 mm; a 40 in tire is 1,016.0 mm.
Each 1 in step adds 25.4 mm. Use the table to translate between "inch" sizes used in truck builds and metric diameters in European data sheets.
| Diameter (in) | Diameter (mm) | Diameter (cm) | Diameter (ft) |
|---|---|---|---|
| 22 | 558.8 | 55.9 | 1.833 |
| 24 | 609.6 | 61.0 | 2.000 |
| 25 | 635.0 | 63.5 | 2.083 |
| 26 | 660.4 | 66.0 | 2.167 |
| 27 | 685.8 | 68.6 | 2.250 |
| 28 | 711.2 | 71.1 | 2.333 |
| 29 | 736.6 | 73.7 | 2.417 |
| 30 | 762.0 | 76.2 | 2.500 |
| 31 | 787.4 | 78.7 | 2.583 |
| 32 | 812.8 | 81.3 | 2.667 |
| 33 | 838.2 | 83.8 | 2.750 |
| 35 | 889.0 | 88.9 | 2.917 |
| 37 | 939.8 | 94.0 | 3.083 |
| 40 | 1,016.0 | 101.6 | 3.333 |
What Is the Tire Diameter Unit Converter?
The Tire Diameter Unit Converter is a tool that converts overall tire height between inches, millimeters, centimeters and feet. Overall diameter is the tire's height from ground to top, unloaded.
US truck and off-road buyers talk in inches; European, Japanese and Australian data sheets list millimeters. The converter removes conversion mistakes when comparing published figures across regions.
Common Uses
This converter has 4 uses: reading foreign spec sheets, garage-height checks, shipping estimates and lift planning.
- Read foreign spec sheets: Convert metric diameters to inches.
- Check garage height: Add tire height to body height in the same unit.
- Estimate shipping: Get box height in cm for courier quotes.
- Plan lifts: Match a metric diameter to inch-based lift guidance.