How does the tyre size calculator work?+
Enter the required inputs, then the calculator applies the displayed formula for tyre sidewall height, overall diameter, rolling circumference and speedometer difference. The result is intended as a practical estimate and should be checked against the relevant manufacturer, service, API or project specification where applicable.
What is the most important input for this tyre size calculator?+
Use a measured or authoritative value whenever possible. For tyre sidewall height, overall diameter, rolling circumference and speedometer difference, the quality of the result depends on the accuracy and units of the inputs you provide.
Can I use this result for planning?+
Yes, for preliminary planning and comparison. For safety-critical, financial-contractual, legal, medical or engineering decisions, verify the assumptions and final values independently.
What inputs does the Tyre Size Calculator use?+
It uses Original tyre width, Original aspect ratio, Original rim diameter, New tyre width, New aspect ratio, and New rim diameter. Follow the unit printed for each field and choose any selectable option to match the real scenario.
What does the Tyre Size Calculator calculate?+
It calculates Original diameter, New diameter, Diameter change, New circumference, and At indicated 100 km/h. With the displayed default inputs, Original diameter is 631.9 mm.
Which formula does the Tyre Size Calculator use?+
The primary relationship is Sidewall = width × aspect ratio ÷ 100. The page also shows substituted values and calculation steps so the result can be checked independently.
How can I verify a Tyre Size Calculator result?+
First verify the units for Original tyre width, Original aspect ratio, and Original rim diameter. Then compare the substituted formula steps with Original diameter and its displayed precision.
What are the limitations of the Tyre Size Calculator?+
Tyre Size Calculator: Treat the result as a mathematical estimate and separately verify input units, rounding rules and any conventions required for your use case.
