Bicycle Tyre Circumference Calculator

The Bicycle Tyre Circumference Calculator estimates your wheel's exact travel distance based on tire width and rim diameter inputs. This tool helps cyclists and mechanics calibrate bike computers for precise speed and distance tracking on every ride. Whether you are installing a new speedometer, swapping tires, or verifying wheel size, this tool provides reliable ISO/ETRTO standard results.

Enter tire width in millimeters (e.g., 23, 25, 28)
Enter rim diameter in millimeters (e.g., 622 for 700c, 559 for 26")

How Tire Circumference Is Calculated

Tire circumference represents the linear distance a bicycle travels in one complete wheel revolution. We use the standard ISO/ETRTO geometric calculation to ensure precision across different bike types. This method is essential because even small errors in size can lead to significant distance discrepancies over long rides.

Circumference = π × (Rim Diameter + 2 × Tire Width)

Where:

  • π = Pi (approximately 3.14159)
  • Rim Diameter = The bead seat diameter of the rim
  • Tire Width = The width of the inflated tire

First, calculate the total diameter by adding the rim diameter to twice the tire width. This step accounts for the tire height above the rim on both sides. Next, multiply the total diameter by Pi (3.14159). This converts the wheel's diameter into the full distance traveled in one rotation. Following these steps ensures your data is accurate and reliable for navigation and training.

What Your Tire Circumference Means

This number tells you exactly how far your bike moves forward with one complete wheel turn. You enter this value into your bike computer to ensure speed and distance data are precise.

Common Calibration Ranges

Road Riding: If your result is between 2050mm and 2140mm, you have a standard road wheel. Using the exact figure helps you track mileage accurately for training or maintenance intervals.

Mountain Biking

Off-Roading: A range of 2250mm to 2350mm indicates a larger 29-inch mountain bike wheel. Setting this correctly is vital for navigating trails and monitoring your average speed on rough terrain.

Pro Tip

To maintain accuracy, re-measure your circumference whenever you change to a different brand or model of tire, as sizing often varies between manufacturers.

Disclaimer: This calculator provides estimates based on standard tire dimensions and assumes tire height equals width. Actual rolling circumference may vary slightly based on specific tire tread, wear, and inflation pressure. For the highest accuracy, perform a physical rollout test.

Check your results against the tire sidewall markings to confirm you entered the correct ETRTO numbers.

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