[TowerTalk] Solid tower legs ?

[Jim Thomson]

I noticed that some tower manufacturers  use solid tower legs.   Pi rod, rohn, and trylon all offer solid leg towers.
On one of Trylons  150 ft free standing towers, the legs start at I believe 2.5 inch solid.   What is the concept behind 
solid legs ?   What am I missing here ?   I mean,  nobody would use a 2 inch  solid mast, poking 14-16 ft  out the top 
of the tower.   A solid mast  would add very extra little strength per the mast software....but a whole bunch of excess weight. 
A mast is not a  tower leg of course but still,  I just dont get it.    After playing around with mast software,  it appears that once 
you get to .25 inch thick, you are better off to increase OD  vs a thicker wall.    IE:  a 3 x .25 mast is a heck of a lot stronger
vs a 2 x .375 mast....and they both weigh the same.  The bigger diam x thinner wall has a bigger sectional modulus.  That all 
assumes the yield strength is identical in both cases. 

Jim   VE7RF