Tire Size and Speedometer Comparison

How to use this tool

1. Enter your values in the labelled fields or load the worked example.
2. Review the assumptions below, then run the tool.
3. Review the result, then copy or download it.

Try this example

{"oldWidth": 205, "oldAspect": 55, "oldRim": 16, "newWidth": 225, "newAspect": 45, "newRim": 17, "indicatedSpeed": 100}

Accuracy and scope

Nominal dimensions only. No fitment, load-rating, clearance, wear or roadworthiness assessment. Width in mm; rim in inches.

Is my data uploaded?

This tool runs locally in your browser. Input and output are not sent to a processing server. Copy or download your result before leaving the page.