In a message dated 98-05-08 01:23:06 EDT, vanagon@VOLKSWAGEN.ORG writes:

<<
 With a bit of math it is easy to figure out the height of a tire and from
 there the circumference of the tire:

 225/70R16 =

 25.4mm = 1"

 225 x .7 x 2 + 406 = 721mm = 28.4"

 225 = how wide the tire is
 70 = % of side wall to width
 2 = two side walls >>

What does "406" stand for in the equation. Michael.