Tire Size Geometry Comparison Calculator
Compare nominal geometric diameters from metric tire size strings.
Your result
EVERYDAYEnter your values and select calculate.
On this page How it works & practical examples
How to use the Tire Size Geometry Comparison Calculator
Compare nominal geometric diameters from metric tire size strings. The speed row assumes the speedometer was calibrated to the original nominal circumference.
The calculation
Worked example
205/55R16 has nominal diameter 631.9 mm; 225/45R17 has 634.3 mm, about 0.3798% larger.
Assumptions and limits
Not a fitment or safety approval. Actual loaded radius, brand dimensions, clearance, load rating and vehicle calibration can differ.
Common questions
Which inputs should I use?
Compare nominal geometric diameters from metric tire size strings. The speed row assumes the speedometer was calibrated to the original nominal circumference.
What does the result exclude?
Not a fitment or safety approval. Actual loaded radius, brand dimensions, clearance, load rating and vehicle calibration can differ.