Tire Sizes and Speedometer Correction


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The attached spreadsheet is set up so that anyone can enter a tire size and get the approximate diameter, widths, and recommended rim width. Axle ratios can also be entered and the engine RPM at 60mph is shown, based on the tire size. The engine RPM can also be entered to check speeds, based on axle ratios and tire sizes. This is a reposting of a thread that I was no longer able to update after the forum site upgrade a couple of years ago.
There is a tab for wheel and tire clearance calculations and a table of axle widths.
A tab that shows original tire sizes.
A tab that shows gear ratios of various Ford transmissions.
A tab that shows tire loads and pressures

Because changing tire diameters will affect speedometer accuracy you can find information and a speedometer gear calculator here:


  • Tire Sizes-v7.xls
    1.3 MB · Views: 0
  • Tire Sizes-v7.xlsx
    1.2 MB · Views: 0