Tire Size Calculator
About Tire Size Calculator
The tire size calculator converts tire width, aspect ratio, and rim diameter into useful tire geometry.
How to Use
The tire size calculator converts tire width, aspect ratio, and rim diameter into useful tire geometry. Fill in New tire width, New aspect ratio, New rim diameter, Old tire width, Old aspect ratio, and Old rim diameter, then review the calculated Diameter, Circumference, Revolutions per mile, Old diameter, Old circumference, Speedometer error, Actual speed at 60 mph, and Speedometer note.
- Open the calculator : Use Tire Size Calculator from the Auto category.
- Check the inputs : Review the required values and any optional settings.
- Read the formula : Use the formula and notes below to understand how the result is produced.
Common Questions
What formula does the Tire Size Calculator use?
Diameter = rim diameter + 2 x sidewall height.
Inputs
- Old tire width
- Old aspect ratio
- Old rim diameter
- New tire width
- New aspect ratio
- New rim diameter
Outputs
- Old diameter
- Diameter
- Old circumference
- Circumference
- Revolutions per mile
- Speedometer error
- Actual speed at 60 mph
- Speedometer note
Formula
Diameter = rim diameter + 2 x sidewall height.