README.md in fitment-0.1.0.1 vs README.md in fitment-0.1.1.1
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+[](https://github.com/rickhull/fitment/actions/workflows/ci.yaml)
+[](http://badge.fury.io/rb/fitment)
+
+# Fitment
+
+This is a library and utility for analyzing and comparing common wheel and
+tire sizes for passenger cars, across most of the globe, but primarily
+considering North America, Europe, Japan, and Korea. Its validity may extend
+somewhat towards passenger trucks and other sorts of utility vehicles.
+
+## Wheels
+
+Wheel diameters are expected to mostly conform to whole inch measurements.
+Half-inch measurements are acceptable but expected to be rare. **This library
+*does not* expect wheel diameters measured in metric units.**
+
+Wheel widths are expected in half-inch increments, measured in inches.
+Expect limited support for wheel widths below 4 inches or above 16 inches.
+
+The location of the hub interface, measured via either "ET" or "offset" is
+also required. "ET" is the most common standard for passenger cars, though
+(particularly American) truck wheels and other rear wheel drive platform
+wheels may come specified with an "offset" rather than "ET".
+
+### ET
+
+*ET* is measured in millimeters from the centerline of the wheel, and may be
+positive or negative. +55 to -55 is common, with positive ETs associated with
+FWD cars (hub towards the outside of the wheel) and negative ETs associated
+with RWD cars (hub towards the inside of the wheel).
+
+### Offset
+
+*Offset* is measured in inches from the outside of the wheel, and is nearly
+always positive, though it may be negative, meaning the hub interface extends
+outside beyond the rim.
+
+## Tires
+
+TBD