In a message dated 12/22/02 5:34:59 AM, Cotsford@AOL.COM writes:

<< Mine works out bigger.    I am using 205/70 x 14.

205 x .7 = 143.5 / 25.4 = 5.64"

(5.64 x 2) + 14 = 25.28" diameter which gives a radius of  12.64"
 >>

Even accepting the invalid use of an equality sign, this calculation ignores
the quantity which is being sought, that being the ROLLING RADIUS.  Perhaps
someone, somewhere is able to consider the many variables involved and with a
sharpened pencil in hand, accurately calculate the rolling radius of a
particular tire, on a particular car, rolling down the highway at a
particular speed, but I can assure you that the equation he uses will have
more than a few elements.

This reminds me of one of my favorite homilies: Measure it with a micrometer;
mark it with a crayon; cut it with a chainsaw.

George