Miata Mailing List: August 1999, Message #430

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Keith's calculations were correct, but to be more precise:

- the 195 width is the tire width at the widest point, not counting markings,
- 50 is the ratio of section height to width,
- the section height is the distance from the rim seat to the top of the 
tread.

However, these measurements are on inflated but unloaded tires, and, under 
load, different tires will deflect differently, resulting in variations in 
loaded height and rolling circumference.  The calculated differences between 
the three tire are not significant.

Jeff Parker