Free · Everyday · Travel & Vehicles

Tire Size Calculator

Compare two metric tire sizes for diameter, circumference, sidewall, revolutions, and speedometer difference.

  • Checked formula
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Calculator inputs

Enter your values

Result

Your calculation

Diameter difference
1.9%
Current / new diameter
26.74 / 27.25 in
Current / new sidewall
123.8 / 117.5 mm
Actual speed at indicated 100 km/h
101.9 km/h

Confirm wheel fitment, load rating, clearance, and manufacturer-approved sizes.

How to use this calculator

  1. Enter the values and choose the units that match your situation.
  2. Calculate to see the primary answer and useful conversions.
  3. Review the assumptions before using the result for a project or decision.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.