Drag Slick question
They say that it is lighter than air,.
This is not significant. N2 is only about 3 % lighter than air
Nitrogen molecules 'are' larger than oxygen molecules but only by about 2 1/2% so "in theory" N2 will have a slightly more difficult time getting out of holes in the tire.
I think the really one or two big advantages to N2 is, that without O2, the tire won't oxidize (deteriorate) internally, and of course this means you are keeping the outside out of the sun!!!!
The big big advantage is that there's no water. THIS is the big thing, really. If you let's say fill the tire from a compressor, operating on a very humid day, and the output is saturated air vapor, this means that on COOL (cold) days, the water vapor is going to condense, which will affect tire pressures
Here's one guy's opinion
http://www.pedrosgarage.com/Site_5/Nitrogen_or_Air.html