A comparison for five relatively common
wheel sizes. The tyre volume was
computed as the volume of a torus
(donut) shape. V = 2*pi^2*R*r^2 =
So tyre volume increases linearly
relative to wheel size and is
proportional to the square of the tyre
diameter. So for instance a 700c x 39mm
tyre will have roughly the same air
volume of a 650Bx40mm tyre. Also a
26x2.3" tyre will only have 91% the
air volume of a 29er 2.3" tyre. One
of these charts includes the 3.7"
wide Surly Endomorph which you can see
has almost 2.5 times the air volume of
commonly available mountain bike tires.