Originally Posted by Ron6519
I see the point of using sonotubes for a fence that high. That size wall will be subjected to some serious wind load at times. I don't think the 10" sonotube will hold up. You will see cracks at the corners in no time due to the small amount of concrete surrounding the post. The 12" sonotube was questionable with the 6" post. Best case scenario would be a 4" post with the 12" tube or a 14-16" tube with the 6" post.
Predicating a sonotube size based on the limitation of a drill bit size is the wrong way to engineer the job.
Ron - thanks for the advice... quick question though. If the hole is drilled with a 10" auger, how easy/difficult would it be to make that hole wide enough to accomodate a 12" sonotube?