In Your Cart:  Tire Sizes  Standard Tire Sizes  Most tire sizes
are specified with two numbers. The first number refers to the
outside diameter of the tire, and the second number refers to
the width. For example, a standard road tire is specified as
700C x 23, which indicates a tire that is approximately 700mm in
diameter and 23mm wide. In actuality, neither of these number is
an exact measurement.  There are five tire diameter sizes that
are in common use on modern standard adult bicycles.  26" is the
most commonly used size for modern mountain bikes and is also
used by many hybrid bikes.  27" is an older size that was used
for road bikes, but since so many bikes were built with this
size, it is still readily available.  27.5" is actually the same
rim diameter as 650B, but is used on mountain bikes. The terms
650B and 27.5" are used somewhat interchangeably; they describe
more or less the same thing.  29" is actually the same rim
diameter as 700C, although most 29" tires will not fit 700C road
rims because t