http://en.wikipedia.org/wiki/Tire_code

2 or 3 digit number: The "aspect ratio" of the sidewall height to the
total width of the tire, as a percentage. If the information is
omitted, it is assumed to be 82%. If the number is larger than 200,
then this is the diameter of the entire tire in millimeters.

On Jul 17, 2011, at 5:27 AM, Harry Hoffman wrote:

>
> Does this ratio somehow become unimportant in the 185s? Or is there
> only
> one ratio offered and that's why the shorthand?