About this application
About Tire Size Calculator
This free Mycelgrid calculator compares the nominal geometry of two metric radial passenger tire sizes. It is designed for a simple, transparent side-by-side calculation in your browser.
Calculation method
Nominal sidewall height comes from section width and aspect ratio. Overall diameter adds two sidewalls to rim diameter; circumference uses π times diameter. Nominal revolutions per mile divide 63,360 by circumference in inches. The speed estimate scales indicated speed by the ratio of new to original nominal diameter.
What it cannot determine
This tool does not identify tires by vehicle, confirm safe fitment, certify load or speed ratings, determine wheel offset, or reproduce real loaded rolling circumference. Tire models with the same printed designation may vary.
Privacy
Runs in this browser. No upload by this tool. Copy/download/export locally. Review before sharing. No account, cloud storage or automatic data persistence is used.
Privacy, data and limits
Tire Size Calculator compares the two tire-size codes and optional indicated-speed value only in this browser page. The tool does not upload these inputs, save a tire-size history, create an account, or provide a cloud copy. Copy, CSV, and print actions run only when you select them.
Dimensions and revolutions per mile use theoretical unloaded tire-size geometry. Real tire measurements and effective rolling circumference vary by tire model, load, inflation and wear. The app does not approve vehicle fitment, load or speed ratings, wheel compatibility, tire clearance, or a safe replacement choice. Verify the specific vehicle, wheel and tire manufacturer requirements before purchase or installation.
For platform-wide practices, read the Mycelgrid Privacy Policy and Terms of Use. For a real product problem or accessibility issue, use Contact Mycelgrid.