Illustrated Explanation of the Chariot System in the Artificers' Record

...portion that treads upon the ground is 3 inches, 6 fenApproximately 1/10th of an inch., 6 li1/100th of an inch., and 6 hao1/1000th of an inch.. This constitutes exactly one-third of the 1 foot 1 inch total. The remaining two-thirds are accounted for by the thickness of the edge where the spokes are seatedOriginal: jian fu. The inner surface of the rim where the spokes are inserted. and the faces of the felloeOriginal: ya. The wooden segments that form the rim of the wheel. near the spokes, which are lacquered.

From a contemporary perspective, there are five reasons why this theory does not hold:

First, in the Record of TradesOriginal: Kao Gong Ji. An ancient Chinese technical encyclopedia compiled during the Warring States period, forming part of the Rites of Zhou., whenever the term "circumference" is used, it invariably refers to something circular. The so-called "felloe circumference" actually refers to the large outer circle of the wheel rim itself; it is a linear measurement derived from its diameter and does not necessarily mean one must measure the girth of the wooden body itself. If one were required to measure the girth of the felloe body, then the inner and outer faces and the top and bottom edges would actually form a rectangle, and thus could not be called a "circumference." This is the first point of disagreement.

Second, the section on The WheelwrightOriginal: Lun ren. The specific chapter of the Record of Trades dealing with chariot construction. states that because the felloe is on the outside of the wheel and treads upon the ground as it travels, it must be exceptionally sturdy. For this reason, its width is made 1 foot 1 inch so that it will not warp or break. If we take the 1 foot 1 inch mentioned in the text as the total sum of all four sides of the girth—rather than the measurement of a single face—then the width of the felloe would only be about 3 inches. There is no logic in making it so narrow and flimsy. This is the second point of disagreement.

For a small cart, the thicknessOriginal: geng. Refers to the depth or thickness of the rim segment. is one-third of an inch...