Uneven tire wear..Yikes!!

["daydreamer36535" <3strong@xxxx>]

Hi all,
in preparation for a trip I was checking the tires out and have found
a problem i'm confused/concerned about.
see pic at http://www.gulftel.com/3strong/tire1.jpg
http://www.gulftel.com/3strong/tire.jpg

This is on a 1974 ambassador, 29'.
So, dual axle and the problem is on one side only.
I see no loose bolts ect.
also it seems this problem occured within the last 1000 miles as I 
just checked the tire pressure before coming home on the last trip.
As you look at the tire, there is DEEP wear for 2-3" then all is well
for about 6" - 16" then another deep wear pattern, all around the
tire. This occured on both tires. Its almost like the tire is 
trying to become square in spots.


What could be the cause?
thanks 
Joe