Now Serving Nitrogen At SuperTireGuy

This is true, but even in the Bayou, the percent of air comprised of
water vapor is less than 1% so
it will likely cause no more of an effect than that. I seriously,
doubt that the racers can control the
other factors which affect tire pressure to 1% (e.g. if the road
increases friction enough to increase
the temp by 3Kelvin that will cause about a 1% increase in Pressure)

 

Scuba tanks are inflated to 3500psi with virtually no moisture. Bike
tires are at what...40psi?

 

Yebbut you don't fill your tanks at a gas station. SCUBA shops have
better stuff with filters/dryers/etc.